Session PC. There are 96 abstracts in this session.

Session: Dynamics, poster number: 067
Towards a Microscopic Theory of the Knight Shift in an Anisotropic, Multiband Type-II Superconductor
Richard Klemm
University of Central Florida, Orlando, Florida
Since the standard theory of Yosida for the Knight shift KS(T)  in a superconductor at the temperature T does not involve the nuclei probed in a nuclear magnetic resonance experiment, Hall and Klemm developed a microscopic theory of the Knight shift in an anisotropic, multiband metal at T = 0.   In the adiabatic limit appropriate for the standard magnetic resonance experiment at finite T, the two Keldysh contours merge into one, and the resulting quantum field theory Green functions can be analytically continued onto the real axis.  We quantizing the quasiparticles in Landau orbits with the Zeeman energy, and diagonalize the BCS Hamiltonian with a Bogoliubov-Valatin transformation.  Preliminary results for a full microscopic theory are favorable.

Session: Dynamics, poster number: 068
Enhancement of singlet-order at natural abundance in a large spin system via bang-bang optimal control
Deepak Khurana; T.S. Mahesh
Indian Institute of Science education and Research, Pune, India
We transfer polarization from a set of high gyromagnetic ratio nuclei (1H ) directly to low gyromagnetic ratio spin-pair (13C-13C) using bang-bang optimal control technique in an 11-spin system. Compared to the standard method not involving polarization transfer, we find an enhancement of singlet order by about 3.4 times. In addition, since the singlet magnetization is contributed by the faster relaxing protons, the recycle delay is halved. Thus effectively we observe a reduction in the overall experimental time by a factor of 23. This method is widely applicable in a variety of systems where a pair of spins with or without chemical equivalence are coupled to a few ancillary spins.

Session: Dynamics, poster number: 069
Solid-state NMR study of ligands on quantum dots: bridging molecular dynamics and thermodynamics
Xueqian Kong; Zhenfeng Pang; Jun Zhang; Xiaogang Peng
Zhejiang University, Hangzhou, China
Ligand exchange can dramatically increase the dispersity of quantum dots without alternating the core structure or synthetic routes. A full set of solid-state NMR investigations have been performed in order to address the mechanisms of ligand exchange and more fundamentally the thermodynamics of dispersion. Based on 13C CODEX, 2H NMR, and 1H-13C DIPSHIFT, we uncovered quantitative information of molecular dynamics of surface ligands. Such information is further converted into thermodynamic parameters i.e. enthalpy and entropy, which is consistent with the measurements based on solubility. Our solid-state NMR approach is an attempt to bridge the gap between molecular dynamics probed at the microscopic level and thermodynamics seen at the macroscopic level.

Session: Dynamics, poster number: 070
Studies of motions and interactions of molecules in ionic liquid electrolytes by nuclear magnetic resonance.  
Pierre Martin1; Michael Deschamps1; Luke O'dell2
1Université d'Orléans, Orleans, France; 2IFM , Deakin University, Geelong, VIC
Due to their unique properties, ionic liquids are interesting candidates for lithium battery electrolytes. However, the difficulty in characterising weak molecular interactions and fast motions between ions means that the liquid « structures » are not fully understood.
Our goal is to quantitatively measure the 7Li-1H HOE transfer in the C3mpyr FSI lithium doped ionic liquid, taking into accounts the longitudinal relaxation times and diffusion effects. Using an expression of the intermolecular dipole-dipole spectral density, we show that the HOE can be interpreted as a measure of the distance of closest approach between spins in weakly interacting ion pairs, and measure the effect of increasing lithium concentration in ILs solutions.

Session: Dynamics, poster number: 071
The cellular health condition severely affects protein folding state in mammalian cells
Kohsuke Inomata; Takanori Kigawa
RIKEN Quantitative Biology Center (QBiC), Yokohama, Japan
In this study, we investigated the correlation between the cellular health condition and the protein folding state in living mammalian cells by using in-cell NMR spectroscopy. Firstly, we employed the centrifuge-based alginate gel encapsulation method for cell immobilization for the bioreactor system in order to establish highly reproducible system. We have then demonstrated by using the modified bioreactor system that the folding state of hAK1 in cells is significantly influenced by the cellular health condition. hAK1 was denatured in cells under stressful culture conditions, while it remained functional and properly folded in cells continuously supplied with fresh medium, indicating that the proper regulation of the physiological condition is crucial. Our results will provide a critical guide to in-cell NMR analyses.

Session: Dynamics, poster number: 072
Simultaneous determination of fast and slow dynamics in molecules using extreme CPMG relaxation dispersion
G Jithender Reddy1; Supriya Pratihar1; David Ban2; Sebastian Frischkorn1; Stefan Becker1; Christian Griesinger1; Donghan Lee2
1Max Planck Institute for Biophysical Chemistry, Goettingen, N/A; 2University of Louisville, Louisville, KY

Molecular dynamics play a significant role for the function of molecule. A critical method that provides the information regarding these dynamics at the atomic level is NMR-based relaxation dispersion (RD) experiments. The RD experiments have been utilized for understanding multiple biological processes occurring at micro-to-millisecond time, such as enzyme catalysis, molecular recognition, ligand binding and protein folding. Here, we applied the recently developed high-power RD concept to the Carr–Purcell–Meiboom–Gill sequence (extreme CPMG; E-CPMG) for the simultaneous detection of fast and slow dynamics. Using a fast folding protein, gpW, we have shown that previous inaccessible kinetics can be accessed with the improved precision and efficiency of the measurement.


Session: Dynamics, poster number: 073
Towards Understanding the Role of Protein Motion in Onco-Proteins That are Drug Targets
Mark Vincent Dela Cerna1; David Ban2; Sengodagounder Arumugam2; Donghan Lee2
1University of Louisville, Louisville, KY; 2James Graham Brown Cancer Center, Louisville, KY
NMR observables such as RDCs report on the amplitude of motions between picoseconds to milliseconds. Here, we present that heterogeneity of average structures underestimate the breadth of Mdmx dynamics through measured 1HN-15N backbone RDCs. In addition, RMSD between experimental and calculated RDC qualitatively recapitulates structural regions showing high variability within the ensemble generated from existing structures. There is also evidence for involvement of allosteric sites in small molecule binding. Results of this project show that conventional average structures do not capture a complete picture of protein dynamics, limiting traditional structure-based drug design. An ensemble generated using techniques that probe dynamics, such as RDC, will introduce a dynamic aspect to drug design, towards development of new therapeutics.

Session: Dynamics, poster number: 074
Probing Solute Organization by Water Proton NMR
Marc Taraban; Katharine T. Briggs; Y. Bruce Yu
University of Maryland, Baltimore, Baltimore, Maryland
Water proton transverse relaxation rate is used to detect and quantify changes in the environment of the water molecules. We demonstrated that the water relaxation rate is sensitive to the presence of protein aggregates within a wide range of the aggregate sizes. Clustering of nanoparticles resulted in water molecules compartmentalization, which in turn affects the water relaxation rate. Interactions of water molecules with amphiphilic macromolecules (fluorinated dendrimer) allow their conformational transitions (dendrimer folding) to be monitored by the water relaxation rate. Mechanisms of the water relaxation rate sensitivity to solute molecule organization are discussed. The large water proton NMR signal intensity makes it possible to detect the transverse relaxation rates from the echo decay using low-field benchtop time-domain NMR spectrometers.

Session: Dynamics, poster number: 075
Droplet NMR: An Integration of Digital Microfluidics (DMF) and High Resolution NMR
Bing Wu1; Ian Swyer1; Sebastian von der Ecken1; Ronald Soong1; Michael Fey2; Armin Beck3; Franck Vincent3; Dieter Gross4; Oliver Gruschke4; Nicolas Freytag3; Till Kuehn3; Martine Monette5; Henry Stronks5; Werner Maas2; Aaron Wheeler1; Andre Simpson1
1University of Toronto, Toronto, Canada; 2Bruker Biospin Corp., Billerica, MA, US; 3Bruker Biospin AG, Fällanden, Switzerland; 4Bruker Biospin GmbH, Rheinstetten, Germany; 5Bruker Biospin Limited, Milton, Canada
High Resolution Nuclear magnetic resonance (NMR) spectroscopy is often considered as the most informative spectroscopic technique as it helps us to gain deep insight into the molecular structure and dynamics. However, compared to many other analytical detection methods, it usually suffers from lower mass sensitivity which is critical for trace analyses as well as bio-sample analyses. In this study, we introduce the first digital microfluidic (DMF) system capable of interfacing droplets of analyte with microcoils within a high-field NMR spectrometer. Droplets can be moved inside the spectrometer to perform a range of routine DMF protocols, while also permitting the acquisitions of several 1D and 2D NMR experiments.

Session: Dynamics, poster number: 076
A Continuous Flow NMR System to study Chemical and Photochemical Waste Water Treatment Processes
Bing Wu1; Rudraksha Datta Majumdar2; Daniel Lane1; Ronald Soong1; Anna Codina3; Kimberly L. Colson3; Werner Maas4; Myrna Simpson1; Andre Simpson1
1University of Toronto, Toronto, Canada; 2Bruker Ltd., Milton, Canada; 3Bruker (UK) Ltd., Coventry, UK; 4Bruker BioSpin Corp., Billerica, MA
Two emerging approaches to quickly degrade small organics are ozone and intense UV light. By irradiating the waste water with UV light many compounds undergo photo-oxidation while ozone can lead to bond cleavage and degradation of numerous chemical moieties. In this study, we exploit the possibility of using a continuous flow NMR system to monitor the transformation processes occurring during the waste water treatment process. 1H NMR was performed on waste water from various plants without preconcentration and undergoing various treatment protocols. The results indicate the great potential of implementing the flow NMR systems to follow complex processes in environmental monitoring and research.

Session: Dynamics, poster number: 077
Magnetic Field-Dependent Lifetimes of Hyperpolarized 13C Spins at Cryogenic Temperature 
Qing Wang
University of Texas at Dallas, Richardson, TX
With the presence of dynamic nuclear polarization (DNP), 13C NMR signal strength has been developed and T1  is more efficient to obtain. In this project, a homebuilt cryogen-free DNP system has been applied to administer the T­1 relaxation time at sweepable magnetic-field at 1.8K of various carboxylates: [1-13C] sodium acetate, [1-13C] glycine, [1-13C] sodium pyruvate, and [1-13C] pyruvic acid. To explore the dependence of 13C T1 with magnetic field, we investigated the relaxation in different fields from 1 T to 9 T. It was found that 13C T1 exhibit power-law dependence with respect to magnetic field with B2.35-3.10 for the carboxyl-containing molecules. This result suggests that the hyperpolarized state for carboxyl contained 13C T1 is strongly increased with ascending field.

Session: Dynamics, poster number: 078

Transition Metal Doping Reveals Link between Electron T1 Reduction and 13C Dynamic Nuclear Polarization Efficiency
Qing Wang
University of Texas at Dallas, Richardson, TX

Benefit from dissolution dynamic nuclear polarization(DNP), sensitivity for NMR on hyperpolarized 13C has been enhanced significantly. It is reported that paramagnetic additives such as lanthanide (e.g. Gd3+, Ho3+, Dy3+, Tb3+) complexes to DNP sample could improve solid-state 13C DNP efficiency. In this project, we explored the effects of paramagnetic transition metal complex R-NOTA (R=Mn2+, Cu2+, Co2+) doping on the efficiency of 13C DNP. Our results exhibit that only Mn2+-NOTA has a substantial development and free radical T1 was significantly reduced in Mn2+-doped samples. This work demonstrates that not all paramagnetic additives are beneficial to DNP and provides a direct evidence that electron T1 reduction is an essential requirement for the improvement in solid-state 13C DNP.


Session: Dynamics, poster number: 079
Characterizing Thermal Mixing Dynamic Nuclear Polarization via Cross-Talk between Spin Reservoirs 
David Guarin1; Sina Marhabaie1; Alberto Rosso2; Daniel Abergel1; Konstantin Ivanov3; Geoffrey Bodenhausen1; Dennis Kurzbach1
1ENS, Departement de Chimie, Paris, France; 2Lab. Physique Théorique et Modèle Statistiques,, Paris, France; 3Novosibirsk State University, Pirogova 2, Novosibirsk, Russia
Thermal mixing (TM) denotes a mechanism for dynamic nuclear polarization (DNP) that efficiently polarize various nuclear spin species. TM relies on triple spin flips that embrace two electronic spins S and S’, and a nuclear spin I. TM entails triple spin flips that enable a heat flow between nuclear and electronic energy reservoirs. This heat flow can induce a transfer of polarization between different nuclear spins I and I'. Based on this feature, we present experimental procedures to identify boundary conditions of TM with respect to radical concentration anbd to quantify the heat flow between reservoirs of different spin species. These experiments allow one to determine whether TM is the dominant mechanism.

Session: Dynamics, poster number: 080
Study of the Surfactant Mutual- and Self- Diffusion in Hydrogel by 1H NMR Chemical Shift Imaging and Slice-selective Diffusion Experiments
Malgorzata Anna Wisniewska; John Georg Seland
Department of Chemistry, University of Bergen, Bergen, Norway
Incorporation of the drug-loaded surfactant micelles into polymer hydrogel is a common method used to achieve controlled drug delivery. The characterization of the diffusion processes in drug delivery system is therefore critical in order to tune the drug loading and release. Here, we present a simple and efficient NMR method to investigate the mobility of the surfactant micelles in hydrogel on micro- and macroscale under non-equilibrium conditions. Our experimental strategy is based on a combination of 1H NMR chemical shift imaging and slice-selective diffusion experiments, which are complementary because of the different time and spatial scales involved. The applications of this approach for comparing candidate hydrogel-based drug delivery systems and for validating their performance will be discussed.

Session: Dynamics, poster number: 081
Recycling up to 10x faster with 3x SNR: Flip-back CP in MAS DNP
Snaedis Björgvinsdóttir; Brennan Walder; Arthur Pinon; Jayasubba Reddy Yarava; Lyndon Emsley
EPFL, Lausanne, Switzerland
We show how the sensitivity of MAS DNP experiments can be improved by the classic flip-back method to recover bulk proton magnetization following continuous wave proton heteronuclear decoupling. Experiments were performed on formulations with characteristic build up times spanning two orders of magnitude: a BDPA radical doped o-terphenyl glass and microcrystalline samples of theophylline, L-histidine monohydrochloride monohydrate, and salicylic acid impregnated by incipient wetness. For these systems, addition of flip-back is simple, improves the sensitivity beyond that provided by modern heteronuclear decoupling methods such as SPINAL64, and provides optimal sensitivity at shorter recycle delays. The shortening of the recycle delay is predicted by numerical simulations using a diffusion model of polarization transport.

Session: Dynamics, poster number: 082
Structural and functional insights into the mode of action of a modular lytic polysaccharide monooxygenase
Gaston Courtade1; Zarah Forsberg2; Ellinor B. Heggset3; Vincent G. H. Eijsink2; Finn L. Aachmann1
1Norwegian University of Science and Technology, Trondheim, Norway; 2Norwegian University of Life Sciences, Ås, Norway; 3RISE PFI AS, Trondheim, Norway
Lytic polysaccharide monooxygenases (LPMOs) are copper-dependent enzymes that bind to the crystalline surface of polysaccharides (cellulose) and cleave β-1,4 glycosidic bonds oxidatively. ScLPMO10C is a cellulose-active LPMO that produces C1-oxidized chain ends. This LPMO has an N-terminal AA10 catalytic domain connected by a linker of 30-amino acids length to a C-terminal family 2 carbohydrate-binding module (CBM). Models of LPMO activity have focused exclusively on the catalytic mechanism, while the role of CBMs and linker in LPMOs is still poorly understood. We have used NMR to probe the dynamic characteristics of full-length ScLPMO10C, revealing conformational flexibility of the linker and the overall shape of the protein. We discuss how the structure and dynamic features of full-length ScLPMO10C guide its biochemical activity.

Session: Dynamics, poster number: 083
Light dynamics of retinal disease relevant rhodopsin G90D mutant
Nina Kubatova
Goethe University, Frankfurt Am Main, Germany
Rhodopsin belongs to the largest GPCRs (G-protein coupled receptor) membrane protein family in the human genome. Light absorption by rhodopsin is the initiation point for photoactivated signaling cascade in retinal rods. Point mutations in the protein sequence cause the defective signaling and lead to human nightblindness diseases such as retinitis pigmentosa (PR) and congenital stationary night blindness (CSNB). Using a combination of NMR spectroscopy and flash photolysis experiments here we characterize the kinetics of the light activation process of the CSNB associated G90D rhodopsin mutant. The introduced mutations lead to significant changes the kinetics of the photodecay of rhodopsin and stability of a protein.

Session: Dynamics, poster number: 084
Spin qubits for quantum simulations: Towards exotic quantum many-body physics
Xinhua Peng1; Zhihuang Luo1; Dieter Suter2; Jiangfeng Du1
1University of Science and Technology of China, Hefei, China; 2Technische Universitaet Dortmund, Dortmund, Germany
The modern conception of phases of matter has undergone tremendous developments since the first observation of topologically ordered states in fractional quantum Hall systems in the 1980s. Topological phase not only plays a significant role in the basic scientific research of condensed matter physics, but also provides a natural medium for fault-tolerant quantum computation. However, the experiments for the exotic matter face the great challenges although they have been intensively and theoretically studied in recent years. Along the lines suggested by Feynman, complex quantum systems can be efficiently simulated on quantum simulators, i.e., programmable quantum systems whose dynamics can be efficiently controlled. Quantum simulations thus offer the possibility to investigate strongly correlated systems exhibiting topological orders and other complex quantum systems that are challenging for simulations on classical computers. Nuclear magnetic resonance is a good test platform for the physical implementation of quantum simulator due to its sophisticated control and precise measurement in multi-qubit experiments. Here using a kind of nuclear magnetic resonance simulator, we experimentally performed quantum simulations of some topological spin models and observed interesting physical phenomena, including the adiabatic transition in the Wen-plaquette model between two different Z2 topological orders and the fundamental signatures of a Z2 topological order in Kitaev toric code model through the measurement of the modular matrices in the first time. Especially the modular matrices characterizes anyonic statistics that are some of the most fundamental finger prints of topological orders. Their measurements by pure experimental means allow one to identify the topological order as well as detect its breakdown in an effective way. Given the special role of anyonic statistics in quantum computation, our work promises myriad applications both in probing and realistically harnessing these exotic phases of matter.

Session: Dynamics, poster number: 085
Experimental Benchmarking of Quantum Control in Zero-field Nuclear Magnetic Resonance
Min Jiang1; Teng Wu2; John Woodland Blanchard3; Guanru Feng4; Xinhua Peng1, 5; Dmitry Budker2, 3
1CAS Key Laboratory of Microscale Magnetic Resonanc, Hefei, China; 2Johannes Gutenberg-University Mainz, Mainz, Germany; 3Helmholtz-Institut Mainz, Mainz, Germany; 4Institute for Quantum Computing and Department of, Waterloo, Canada; 5Synergetic Innovation Center of Quantum Informatio, Hefei, China
Experimental characterization of the controllability and quality of the level of coherent control in a specific quantum architecture is a central problem in contemporary experimental physics and an important ingredient to improving performance.This kind of benchmarking experiments has not been demonstrated in zero-field NMR. Here we realize a composite-pulse technique for both arbitrary one-spin rotations and a two-spin controlled-not (CNOT) gate in a heteronuclear two-spin system at zero field, which experimentally demonstrates universal quantum control in such a system. Moreover, using randomized benchmarking and partial quantum process tomography, we evaluate the quality of the control, achieving for single-spin control for 13C with an average fidelity of 0.9960(2) and two-spin control via a CNOT gate with a fidelity of 0.9877(2).

Session: Dynamics, poster number: 086
Describe PFG anomalous diffusion by fractional modified-Bloch equations and other methods
Guoxing Lin
Chemistry Dept of Clark Univ, Worcester, MA
Anomalous diffusion has been observed in many polymer or biological systems. Pulsed-field gradient (PFG) anomalous diffusion can be described by various methods recently developed based on fractional calculus such as the modified-Bloch equation method, the effective phase shift diffusion equation method, the non-Gaussian phase approximation method, etc. These theoretical results and continuous time random walk (CTRW) simulation can be applied to study free anomalous diffusion, restricted anomalous diffusion, and anisotropic anomalous diffusion in NMR and MRI.

Session: Dynamics, poster number: 087

Application of methyl-TROSY to a large paramagnetic membrane protein without perdeuteration: 13C-MMTS-labeled NADPH- cytochrome P450 oxidoreductase


Azamat Galiakhmetov1; Elizaveta A. Kovrigina2; Chuanwu Xia2; Jung-Ja P. Kim2; Evgenii L. Kovrigin1
1Marquette University, Milwaukee, WI; 2Medical College of Wisconsin, Milwaukee, WI

NMR spectroscopy studies of structure and dynamics of membrane proteins involved into electron transfer are challenging due to paramagnetic relaxation and the presence of a lipid bilayer. Here we applied the extrinsic labeling with 13C-methyl groups to probe conformational changes and redox states of NADPH-cytocrome P450 oxidoreductase (POR) in lipid nanodiscs. We first interrogated a soluble POR fragment to show that signals from methyl labels located in different parts of the POR molecule differentially respond to protein reduction with NADPH and a conformational change. Incorporation of a full-length POR in a lipid nanodisc resulted in a 240kDa complex yet producing detectable signals from both oxidized and reduced POR at 600MHz without perdeuteration.



Session: Dynamics, poster number: 088
Accurate Determination of 19F Chemical Shift Tensors in Fluorosubstituted Tryptophans and HIV-1 CA Assemblies by DFT and MAS NMR Spectroscopy.
Sucharita Sarkar
Graduate Student, Newark, DE

19F is an excellent NMR probe for applications in biochemical studies due to its favorable magnetic and chemical properties. We examined chemical shift parameters of fluorine-substituted crystalline tryptophan and assemblies of HIV-1 CA protein, by magic angle spinning (MAS) solid-state NMR spectroscopy and density functional theory (DFT). We assessed the dependence of the experimental 19F chemical shift tensor (CST) parameters on the fluorine position in the aromatic ring, the chirality of the tryptophan molecule, and the location of the tryptophan residue in the CA protein. Our results reveal that high-quality DFT calculations need to take into account the local crystal symmetry of the molecule employing PBE0 functional with a 50% Hartree-Fock exchange term to obtain the most reliable results.


Session: Dynamics, poster number: 089
MRI velocimetry of dynamics based on the Lorentzian force in electrochemical cell 
Stefan Benders1; Bruna Gomes2; Marcelo Carmo3; Bernhard Blümich1
1RWTH Aachen University, Aachen, Germany; 2Universidade de São Paulo, São -Carlos, Brazil; 3Forschungszentrum Jülich, Jülich, Germany
Electrochemical reactions are a crucial part of modern technologies such as batteries. MRI has evolved to a powerful tool to gain deeper insights into these processes. A problem arising with this methodology is the influence of the magnetic field on the process itself. Since an electrochemical cell features moving ions and therefore moving charges, a magnetic field will cause Lorentz forces, also known as the magnetoelectrolysis effect. Depending on the orientation of the electrodes with respect to the magnetic field direction, different flow patterns are observable. This motion inherently effects measurements of electrochemical cells and therefore characterization of the flow field is crucial. This study uses phase-contrast velocimetry (FLIESSEN, spin echo velocity imaging) to analyse these flow-patterns under in-situ conditions.

Session: Dynamics, poster number: 090
Application of bullet-DNP to produce long-lived hyperpolarized fumarate
James Eills; George Bacanu; Karel Kouril; Hana Kourilova; Malcolm Levitt; Benno Meier
University of Southampton, Southampton, United Kingdom
Nuclear spins can be hyperpolarized to dramatically enhance NMR signal strength, but the hyperpolarized signals decay with the T1 relaxation time. We have recently shown it is possible to extend the lifetime of 13C nuclear spin polarization in fumarate by temporarily precipitating the molecules out of solution. We apply the novel bullet-DNP technique to generate hyperpolarized fumarate, and fire the bullet into an acid solution. This precipitates the fumarate as a pure solid, and dissolves the glassing agent and free radicals necessary for DNP. The pure fumarate has an increased T1 compared to the solution, and after some storage time in the solid, can be dissolved to detect a hyperpolarized solution-state NMR signal.

Session: Dynamics, poster number: 091
Searching for dark matter with zero- to ultralow-field NMR
Antoine Garcon1, 3; John Blanchard1; Gary Centers1, 3; Nataniel L. Figueora1, 3; Marina Gil Sendra1, 3; Arne Wickenbrock1; Dmitry Budker1, 2
1Helmholtz Institute, Mainz, Germany; 2UCB Physics, NSD LBNL, Berkeley, CA; 3Johannes Gutenberg university, Mainz, Germany
Elucidating the nature of dark matter will profoundly impact our understanding of cosmology and particle physics, providing key insights into physics beyond the Standard Model. Recent theories of couplings between dark matter and nuclear spins have opened the possibility of directly detecting axion and dark-photon dark matter via NMR spectroscopy. The Cosmic Axion Spin Precession Experiment (CASPEr) is multi-faceted NMR search for such particles. We present new limits from a CASPEr experiment operating at zero- to ultralow-field NMR (ZULF NMR). We briefly review the physical principles enabling the detection of dark-matter via ZULF NMR and show the current ZULF NMR apparatus. We then introduce exotic measurement and data processing schemes used in our searches.

Session: Dynamics, poster number: 092

Field-dependent high-resolution spectral density mapping using a fast, mechanical-based shuttle system


Sebastian Frischkorn1; Ching-Yu Chou2; Stefan Becker1; Christian Griesinger1
1Max-Planck-Institute for Biophysical Chemistry, Göttingen, Germany; 2Field Cycling Technology Ltd., Hsinchu, Taiwan

Protein motions are crucial for biological function, from protein-protein interaction to ligand recognition and enzymatic kinetics. The relaxation properties of a certain biomolecule encode for these motional characteristics. The use of relaxation experiments requires strong magnetic fields in the case of protein NMR to provide the necessary resolution and sensitivity for a site-specific analysis. Therefore we use a mechanical-based shuttle NMR approach to measure relaxation experiments at low fields (< 1 T) while retaining the sensitivity and resolution of a high field spectrometer. The so-obtained field-dependent relaxation data is analysed in respect of the spectral density behaviour at a broad field range.


Session: Dynamics, poster number: 093
Quantitative MR Fingerprinting (MRF) Chemical Exchange Saturation Transfer (CEST) with Deep Learning Reconstruction
Ouri Cohen1, 2; Christian T. Farrar1, 2; Bo Zhu1, 2; Matthew S. Rosen1, 2
1A.A. Martinos Center for Biomedical Imaging, Charlestown, MA; 2Harvard Medical School, Boston, MA
MR Fingerprinting (MRF) allows accurate simultaneous quantification of multiple tissue parameter maps. In practice, however, the accuracy of reconstruction is limited by the resolution of a matching dictionary whose size grows exponentially with the number of reconstructed parameters. In previous work, we demonstrated the feasibility of using
a neural network (NN) trained on simulated data to extract T1 and T2 maps from measured data. Here we extend the reconstruction to a significantly larger set of parameters.

Session: Dynamics, poster number: 094
Dynamic Activation and Regulation of the Mitogen-activated protein kinase p38
Senthil Ganesan
University of Arizona, Tucson, Arizona
Enzymes, including kinases, require conformational and dynamic changes to perform their biological function. Here, we use auto-correlated 15N fast (ns-ps) and intermediate timescale (us-ms) dynamics measurements to understand the activation and regulation of a kinase called p38. Interestingly, we did not see any correlation between catalytic activity and dynamics in p38. Indeed, when we tried to globally fit relaxation dispersion profiles we were unable to do so in a statistical meaningful manner. To overcome this problem, we clustered residues with similar exchange dynamics using Bayesian Information Criterion (BIC). Using this approach, we provide direct experimental evidence of dynamic collaboration within p38 (without apparent structural changes) and show that dynamics at different timescale control step-wise assembly towards its enzymatic competent state.

Session: Dynamics, poster number: 095
Enhancing the detection of edges and non-differentiable points in an NMR spectrum using delayed-acquisition
Zhaoyuan Gong; Jamie Walls
Department of Chemistry, University of Miami, Coral Gables, FL
In delayed-acquisition experiments, differences in T2 values, which are often the result of differences in the underlying spin dynamics and/or complexity, can be exploited to improve resolution by suppressing the broad signals from fast, T2-relaxing species relative to the sharp signals from slow, T2-relaxing species. In this work, an alternative source of differential, ''Fourier dephasing'' under delayed-acquisition is demonstrated whereby signals associated with frequencies where the line shape either changes sharply and/or is non-differentiable at some finite order dephase at a much slower rate than those associated with frequencies where the line shape is smooth, independent of the underlying dynamics and/or complexity. Experimental demonstrations of Fourier dephasing in liquids, liquid/liquid interfaces, and solids are presented.

Session: Dynamics, poster number: 096
ssNMR Guided Competitive Adsorption to Force Reactions into Specific Zeolite Micropores
Sambhu Radhakrishnan; Alexy Kubarev; Maarten Roeffaers; Johan Martens; Francis Taulelle; Eric Breynaert
KU Leuven - Surface Chemistry and Catalysis, Leuven (3001), Belgium
Competitive adsorption is an unexploited tool to tailor shape-selective catalysis in micropores of zeolite catalysts. ssNMR approaches, including combination of 13C Hahn-echo, 1H–13C CP, quantititive 1H NMR enable investigation of competitive adsorption. Spectral evolution, chemical exchange effects and combination with confocal laser scanning microscopy locate solvent and reactants on specific adsorption sites. Two showcase liquid state reactions heterogeneously catalysed by two different zeolites, ethanol etherification of β-citronellene on zeolite beta and furfuryl alcohol oligomerization on ZSM-5, demonstrate the principles of NMR detected competitive adsorption to guide reaction selectivity.
Refs: Radhakrishnan et al., JACS, 138, p.2802 (2016); Kubarev et al., ACS Catal., 7, p.4248 (2017); Houlleberghs et al., Anal. Chem., 89, p.6940 (2017).

Session: Dynamics, poster number: 097
T1s for Nothing and Flips for Free: Mapping Magnetization Decay in Hyperpolarized MRI with No Additional Data Collection
Peter Niedbalski1; Matthew Willmering1; Scott Robertson2; Zackary Cleveland1
1Cincinnati Children's Hospital, Cincinnati, OH; 2Duke University Medical Center, Durham, NC
Hyperpolarized media are ubiquitous in basic and applied research (e.g., catalysis and biomedicine). Unfortunately, it is difficult to extract quantitative information from HP nuclei, because magnetization decays due to RF and T1, which vary across a sample. While decay can be corrected by flip angle and T1 mapping, these additional measurements are often impractical and increase experimental difficulty and cost. We demonstrate magnetization loss can be quantified without additional measurements. Using radial MRI, signal intensity, and thus dynamic magnetization decay, is encoded simultaneously with spatial information. Decay is then extracted from time-domain data using keyhole image reconstruction. This approach is validated via simulation and phantom experiments, and as proof-of-principle example, applied to human HP 129Xe ventilation imaging.

Session: Dynamics, poster number: 098
Propagated Perturbations from a Peripheral Mutation Show Interactions Supporting WW Domain Thermostability and Function
Meiling Zhang
University of Notre Dame, Notre Dame, IN
Accurate prediction of hypersensitive mutation sites remains a nontrivial challenge. We illustrate this challenge in a study of an isosteric mutation (Q33E) at the edge of Pin1 WW that has eluded previous studies. The mutation unexpectedly causes drastic losses of the domain’s thermostability and functions. Underlying the decreased thermostability, we observe propagated conformational perturbations. 15N CPMG RD experiments indicate Q33E-WW undergoes a global exchange process between an unfolded (2.6%) and folded state at 278K. CSPs highlight weakened cross-strand H-bonds and hydrophobic cores essential for the architecture of the domain. 10μs MD trajectories of Q33E-WW and WT-WW suggest that Q33E creates an electrostatic “wedge”, which pries apart the neighboring conserved hydrophobic core essential for WW domain thermostability.

Session: Dynamics, poster number: 099
Functional Implications of Active Site Loop Dynamics of Protein Tyrosine Phosphatases
Victor Beaumont
Yale University, New Haven, CT
Research elucidating the contribution of loop motions to the mechanism of protein tyrosine phosphatases (PTPs) is directed via two approaches. First, characterization of the rates of hydrolysis and active site loop motions in Vaccinia H1-Related (VHR) PTP gives insight to general PTPs because VHR possesses the minimal PTP catalytic core. Preliminary data shows that the acid loop closes at a rate of 23 s-1, which is similar to the catalytic rate. Secondly, a chimeric construct of Yersinia outer protein H (YopH) with an active site loop from PTP1B informs on the contribution of the amino acid sequence to the kinetics. Given the slower catalytic rate and lack of dynamical motions of the chimera, loop motions are more complicated than anticipated.

Session: Dynamics, poster number: 100
Quantification of Spectroscopically Resolved Glycerol and Water Exchange in Human Aquaporins with Diffusion Exchange Methods
Sarah Mailhiot; Sofia de Mare; Karin Lindkvist-Petersson; Daniel Topgaard
Lund University, Lund, Sweden
Exchange NMR is well suited for studying diffusion across the cellular membrane. Previous NMR methods measured the transport of water across the cellular membrane, but for membrane proteins that co-transport molecules more information is needed. In this work, we propose a filter exchange diffusion NMR method that measures the exchange of water and glycerol simultaneously. Using this method and modeling, the ratio of water to glycerol molecules transported across the cellular membrane by human aquaporin proteins is measured non-invasively. 

Session: Dynamics, poster number: 101
Measuring Molecular Parity Nonconservation Using Nuclear-Magnetic-Resonance Spectroscopy
James Eills1, 2; John Blanchard3; Lykourgos Bougas2; Mikhail Kozlov4, 5; Alex Pines6, 7; Dmitry Budker2, 8
1University of Southampton, Southampton, United Kingdom; 2Johannes Gutenberg-Universität Mainz, Mainz, Germany; 3Helmholtz-Institut Mainz, Mainz, Germany; 4Petersburg Nuclear Physics Institute, Gatchina, Russia; 5St. Petersburg Electrotechnical University LETI, St. Petersburg, Russia; 6Materials Science Division, LBNL, Berkeley, CA; 7Department of Chemistry, University of California, Berkeley, CA; 8UCB Physics, NSD LBNL, Berkeley, CA

The weak force violates parity, but detection of parity nonconservation (PNC) in molecular systems remains a major experimental challenge. We describe a nuclear magnetic resonance (NMR) experiment in which we titrate the chirality (enantiomeric excess) of a solvent and measure the diasteriomeric splitting in the spectra of a chiral solute in order to search for an anomalous offset due to PNC. In the proof-of-principle experiment, we search for PNC in the 13C resonances of small molecules, and use the 1H resonances, which are insensitive to PNC, as an internal reference. Preliminary experiments have set a constraint on molecular PNC in 13C chemical shifts at a level of 10−5 ppm. We will discuss progress toward future NMR-based searches for molecular PNC.


Session: Dynamics, poster number: 102
DNA Polymerase β a Moving Target: Transitions in us-ms Dynamics
Eugene F Derose1; Thomas W Kirby2; Geoffrey A Mueller2; William A Beard2; Samuel H Wilson2; Robert E London2
1NIEHS Contractor, Research Triangle Park, NC; 2National Inst. of Environmental Health Sciences, Research Triangle Park, NC
DNA polymerase β (pol β) plays a central role in the DNA base excision repair pathway and also serves as an important model polymerase.  Dynamic characterization of the apoenzyme and DNA/dNTP complexes of pol β from methyl-TROSY 13C-1H multiple quantum CPMG relaxation dispersion experiments, reveals transitions in us-ms dynamics in response to substrate binding. The side chain dynamics is initially localized in the DNA binding subdomain of the apoenzyme  (kex ~ 1900 s-1) and may contribute to DNA binding.  The side chain dynamics becomes delocalized and uncoupled throughout the enzyme after binding a 1-nucleotide gapped damaged DNA substrate.  The dynamics then transitions to the Catalytic subdomain (kex  ~ 1200 s-1), suggesting that the side chain dynamics may play a role in catalysis.

Session: Dynamics, poster number: 103
Overhauser liquid Dynamic Nuclear Polarization and in-situ Electron Paramagnetic Resonance at 14.1 T – 395 GHz

Thierry Dubroca1; johan van Tol1; Bianca Trociewitz1; Frederic Mentink-Vigier1; Sungsool Wi1; William W. Brey1; Lucio Frydman3; Joanna R. Long4; Stephen Hill2
1National High Magnetic Field Lab, Tallahassee, FL; 2National High Magnetic Field Lab / FSU, Tallahassee, FL; 3Weizmann Institute, Rehovot, N/A; 4University of Florida, Gainesville, FL
We illustrate our instrumentation development progress by presenting enhancements of 160 for 31P and 41 for 13C nuclei at room temperature in large volume samples (100 µL) that were obtained using a 395 GHz gyrotron at 14.1 T (1H 600 MHz) via Overhauser DNP mechanism in the liquid state. Also, we will present our most recent instrumentation upgrade, which includes an in-situ electron paramagnetic resonance spectrometer (EPR) based on a 395 GHz Virginia Diodes microwave source, along with continuous-wave and pulsed EPR spectra obtained for various DNP radicals. A microwave field of 0.8 Gauss/Watt1/2 at the sample is demonstrated for our homebuilt liquid DNP large sample volume probe. NSF-MRI CHE-1229170, NSF DMR-1157490, and the State of Florida.

Session: Dynamics, poster number: 104
Insights into structure and function of an ion channel by ultrafast magic angle spinning NMR 
Tobias Schubeis; Andrea Bertarello; Marta Bonaccorsi; Tanguy Le Marchand; Jan Stanek; Guido Pintacuda
CNRS - ENS Lyon, Lyon, France
We challenge the capacity of solid-state NMR at > 100 kHz magic-angle spinning (MAS) on the bacterial divalent cation channel CorA, a pentamer of 5 x 42 kDa, comprised of two transmembrane helices and a large cytoplasmic domain, hosting various metal binding sites (usually for Mg2+ or Co2+). We present strategies to obtain sequence-specific chemical shift information, which gives insight into the secondary structure, as well as experiments that report on motions of different time scales. We finally discuss how this unique residue-specific information can be used to describe the transport of ions through the CorA channel. The data presented is complementary to already available crystal and cryo-EM structures, and represents a powerful example of integrated structural biology.

Session: Dynamics, poster number: 105
Dynamics and rigidity in the intact fd(y21m) bacteriophage probed by automated analysis of ssNMR experimental data
Tom Aharoni; Amir Goldbourt
School of Chemistry, Tel Aviv University, Tel Aviv, Israel
The filamentous bacteriophage fd is a ssDNA virus packaged by thousands of identical copies of a helical coat protein. CSA recoupling ssNMR experiments show that for the coat protein bearing a y21m mutation, residues located in the helical part are rigid and are associated with tight hydrophobic packing of the phage. Motional amplitudes in the N-terminus are smaller and monotonically increase. In order to analyze the results efficiently and reliably, we developed a software, which is able to automatically assign the spectral cross peaks and output all the CSA line shapes. This approach is general and can be applied to study different interactions such as relaxation rates, dipolar order parameters.

Session: Dynamics, poster number: 106
Protein Rotational Dynamics Probed By Anisotropic T NMR Relaxation Data In Aligned Lipid Bilayers
Emmanuel O. Awosanya; Alexander A. Nevzorov
North Carolina State University, Raleigh, NC
Residue-specific 15N T relaxation times have been determined by fitting the decay of resolved two-dimensional SAMPI4 resonances for Pf1 coat protein reconstituted in DMPC/DHPC bicelles as a function of the incorporated spin-lock time. Uniaxial rotational diffusion model yields a linear correlation of R relaxation rates with respect to bond factor sin4θB, where θB is the angle that NH bond forms relative to the axis of rotation. The value of the diffusion coefficient of D|| = 8.0×105 s-1 was determined from the simple linear regression of R data. Fitting of R data of assigned transmembrane domain of Pf1 to a wave-like pattern yielded a close value of D|| = 7.7×105 s-1. These diffusion coefficients correspond to bilayer viscosity of ~1 Poise.

Session: Dynamics, poster number: 107
SABRE SHEATH’ed: Easy Optimization via in situ Detection at Zero Field and Hours-Long Continuous Operation
John W. Blanchard1, 3; Barbara Ripka2; Teng Wu1, 3; Kerstin Muennemann2, 4; Dmitry Budker1, 3
1Helmholtz-Institut Mainz, Mainz, Germany; 2MPI for Polymer Research, Mainz, Germany; 3Johannes Gutenberg University, Mainz, Germany; 4Technische Universitaet Kaiserslautern, Kaiserslautern, Germany
Zero- to Ultralow field NMR (ZULF NMR) is able to measure SABRE-SHEATH (SABRE in SHield Enables Alignment
Transfer to Heteronuclei) enhancements without the necessity to move the sample between shield and spectrometer, thus
constituting a fully reproducible experimental environment for SABRE-SHEATH. By applying a varying microtesla
magnetic field during polarization transfer we were able to confirm recently published results on SABRE-SHEATH.
Creating hyperpolarization continuously and in situ makes SABRE particularly appealing for long-time precision
measurements with ZULF NMR, that do not tolerate interruptions and changes in setup. In this work it was demonstrated
that Pyridine can be polarized continuously at ZULF for over 4h, at a resolution that allows to resolve identifying spectral
features.

Session: Dynamics, poster number: 108
Optimizing NMR hardware and pulse sequences with CapPack™ devices
Lingyu Chi1; Ming Huang1; Annalise Pfaff1; Rex Gerald3; Jie Huang2; Klaus Woelk1
1Department of Chemistry, Missouri S&T, Rolla, MO; 2Department of ECE, Missouri S&T, Rolla, MO; 3American Inventor Institute, Willow Springs, IL
CapPack™ devices are capillary-tube assemblies developed for the evaluation and optimization of NMR hardware, pulse sequences, and parameters. They subdivide the existing sample volume (e.g., 5-mm NMR tube) into smaller volumes that are isolated from each other (e.g., 360-µm capillaries). Depending on the application, the individually glass-sealed capillaries may contain the same or different NMR-sensitive solutions. This contribution focuses on two different CapPack™ device geometries, which were assembled for two different performance tests: (1) a 10-capillary side-by-side gradient CapPack™ for monitoring the on- and off-resonance performance of adiabatic hyperbolic secant pulses and (2) a seven-capillary clustered T1 CapPack™ for examining the T1 robustness of the solvent suppression sequence EXCEPT.

Session: Dynamics, poster number: 109

The Chemical Shift Z-score for assessing Order and Disorder in Proteins


Jakob Toudahl Nielsen1, 2; Frans Mulder1, 2
1Aarhus University, Aarhus, Denmark; 2Aarhus University, Aarhus, Denmark

Our Chemical Shift Z-score for assessing Order and Disorder in Proteins (CheZOD Z-scores) quantifies the deviation from random coil chemical shift (RCCS) and correlates with local order/disorder of a protein - revealing:

(i)            By analyzing sequence specific CheZOD Z-scores for 117 proteins that there is order in disorder1.

(ii)           A new method, POTENCI for predicting RCCSs from sequence outperforming the currently most authoritative methods2.

(iii)          Principle component analysis of the signed deviation from RCCS discriminates between the different secondary structures and identify hydrogen bonding.

(iv)          Using CheZOD Z-scores for at protein set to benchmark and rank the performance of a large set of widely used software for predicting disorder from sequence in proteins.


Session: Dynamics, poster number: 110
Revisiting the Longitudinal Relaxation of Hyperpolarized Nuclear Spin States
Klaus Woelk
Missouri S&T, Rolla, MO
Hyperpolarization techniques are frequently used to achieve enhanced signal intensities in NMR spectroscopy, or increased contrast in MRI. It was found experimentally that some forms of hyperpolarization relax much faster than polarization generated, for example, by a 180° pulse in an inversion-recovery experiment. A mathematical treatment of relaxation matrices provides eigenvalues and eigenvectors that shed new light on the longitudinal relaxation of nuclear spin hyperpolarization. As a consequence, the accelerated relaxation found experimentally does not conflict with the general theory of longitudinal relaxation but may actually be an anticipated result of it. With the newly gained insight, it is possible to design selective NMR experiments that can extend the lifetime of hyperpolarization in targeted molecules.

Session: Dynamics, poster number: 111
Solution NMR Studies on the Mechanisms underlying Activation of Deubiquitinase A by Phosphorylation
Ashish Kabra; Ying Li
University of Louisville, Louisville, Kentucky
Deubiquitinase A (DUBA) is a cysteine protease that negatively regulates the production of proinflammatory cytokines. DUBA recognizes polyubiquitin substrates formed via isopeptide bond linkages. We used solution NMR, in combination with biochemical assays, to define the intramolecular interactions essential for DUBA activity. The weak interactions between the N-terminal disordered fragment, which contains a phosphorylated serine in the active form of DUBA, and the well-folded domain of DUBA were characterized by paramagnetic relaxation enhancement. Microsecond-to-millisecond conformational dynamics of DUBA were characterized by amide 1H Carr-Purcell-Meiboom-Gill experiments. The effects of phosphorylation on the structure and dynamics of DUBA were quantified by comparison of phosphorylated and unphosphorylated forms of DUBA.

Session: Dynamics, poster number: 112
Enhanced NOE Ensemble Determination Incorporating Hierarchical Kinetics 
Colin Smith1, 2; Adam Mazur2, 4; Ashok Rout2; Christian Griesinger2; Donghan Lee2, 3; Bert de Groot2
1Wesleyan University, Middletown, CT; 2Max Planck Institute for Biophysical Chemistry, Göttingen, Germany; 3University of Louisville, Louisville, KY; 4University of Basel, Basel, Switzerland
Nuclear Overhauser effect (NOE) experiments are used ubiquitously for solving protein structures. The goal of this work is to create much more accurate NOE structural ensembles. We advance several key areas: incorporating an explicit orientation dependence, taking into account motion at different timescales, and explicitly modeling the effect of spin diffusion. We have developed a new method that can be used to calculate NOE buildup curves from an ensemble of structures, and then iteratively improve those ensembles. While most structure determination methods assume distances average as 1/r^6, our results suggest that 1/r^3 or a hybrid approach is more appropriate. An analysis of a large set of crystal structures suggests that NOE data contains a significant amount of high resolution information.

Session: Dynamics, poster number: 113
Residue-Specific Interactions of Intrinsically Disordered Proteins with Silica Nanoparticles  and Their Quantitative Prediction
Mouzhe Xie; Da-Wei Li; Alexandar Hansen; Jiaqi Yuan; Rafael Brüschweiler
The Ohio State University, Columbus, OH
Intrinsically disordered proteins (IDP) play important regulatory roles, and their dysfunctions are linked to many diseases. In biomedicine, attempts have been made to alter IDP functions using nanoparticles, which calls for better understanding of the physical-chemical driving forces. Here, we report the binding profiles of four different IDPs with silica nanoparticles (SNPs) using spin relaxation experiments. A novel Free Residue Interaction Model was then developed to demonstrates how the interplay of attractive and repulsive Coulomb interactions with hydrophobic effects is responsible for the sequence-dependent interactions. We further employed coarse-grained molecular dynamics to systematically study the individual contributions. This work represents the first quantitative study of IDP-SNP interactions, which should guide the design of next-generation nanoproducts for better healthcare.

Session: Dynamics, poster number: 114
Detection of oil under arctic ice with earth's field nmr
Mark Conradi; Stephen Altobelli; Eiichi Fukushima
ABQMR, Albuquerque, NM
   We have developed earth's field nmr for detection of spilled oil trapped under or in arctic ice. Three nmr issues arise: (1) pre-polarization is required and requires 12 kW and must be removed in 10 msec because of the short oil T1. (2) Adiabatic sweep pulses are required because of the inhomogeneous B1; the sweep pulses must avoid frequencies near zero and be insensitive to complications from the counter-rotating field. (3) The overwhelming signal of sea water must be severely attenuated to detect the much smaller quantity of oil. This is done on  the basis of T1 (0.1 and 2 sec for oil and water). 

Session: Dynamics, poster number: 115
Conformation and Dynamics of the Orphan Nuclear Receptor Ftz-F1 
Nicolas Daffern
Northwestern, Evanston, IL
Nuclear receptors (NRs) are an important family of transcription factors that are ubiquitous in metazoans. They control processes such as development, reproduction, and metabolism and are medically relevant, as almost one out of six therapeutics in the clinic act on NRs as the primary target. NRs harbor two conserved functional domains; the ligand-binding domain (LBD), which binds to small molecules like hormones and metabolites, and the DNA binding domain, which directs the NR to specific DNA sequences. The structural mechanisms that regulate NR LBD function are poorly understood even though this domain engages in interactions with multiple partners and is thought to undergo significant conformational changes while performing its regulatory functions. Almost all current knowledge is based on crystal structures at liquid nitrogen temperatures. We are using 15N spin relaxation experiments, along with mutagenesis and molecular dynamics (MD) simulations, to characterize the conformation and dynamics of the LBD of an orphan NR called Ftz-F1 in Drosophila melanogaster. Unlike canonical ligand-binding NRs, Ftz-F1 appears to be constitutively active, most likely due to a short alpha helix (6) which occupies the ligand-binding pocket in the crystal structure. We have almost completely assigned all the observable backbone resonances (which translates to >90% of expected resonances) for Ftz-F1 LBD and established that the domain when bound to its coactivator Ftz adopts a conformation in solution that closely resembles the one observed in the crystal. However, our spin relaxation experiments suggest that several regions of the protein, most notably α6 residues, undergo both fast (picosecond-nanosecond) and slow timescale (microsecond-millisecond) motions; residues lining the ligand-binding pocket as well as those near the Ftz coactivator-binding site also exhibit microsecond-millisecond timescale motions. We have performed MD simulations of Ftz-F1 LBD to rationalize these observations. The results of our NMR studies and those from molecular dynamics simulations will be presented.

Session: Dynamics, poster number: 116
Measurement and Characterization of Hydrogen–Deuterium Exchange Chemistry Using Relaxation Dispersion NMR Spectroscopy

Gennady Khirich
Genentech, Inc., South San Francisco, CA
One-dimensional relaxation dispersion at 13C natural abundance successfully characterized the kinetics and thermodynamics of the HDX reaction occurring at Nε in arginine by monitoring Cδ in varying amounts of D2O. A small equilibrium isotope effect was observed and quantified (ΔG=−0.14 kcalmol-1). A diffusion-controlled rate constant of kD=5.1×109 s–1M–1 was determined from the pH*-dependence of kex . Δω was measured to be 0.12 ppm from fitting D2O-dependent dispersion profiles collected at a single static field. ΔG was used to bridge the millisecond lifetimes of the detectable positively charged arginine species with the shorter nanosecond lifetime of the invisible neutral arginine intermediate to characterize the equilibrium lifetimes of the various arginine species in solution as a function of fractional solvent deuterium. 

Session: Dynamics, poster number: 117

NMR dynamics study of the active and inactive isoforms of a type III antifreeze protein


Seo-Ree Choi; Na-Hyun Kim; Ae-Ree Lee; Joon-Hwa Lee
Gyeongsang National University, Jinju, Korea, Republic of

The type III antifreeze proteins (AFPs) prevent the growth of ice crystals within organisms living in polar regions. The type III AFPs have been categorized into two subgroups, quaternary-amino-ethyl (QAE) and sulfopropyl (SP) sephadex-binding isoforms, based on differences in their isoelectric points, and the QAE proteins can be further divided into QAE1 and QAE2 subgroups. The QAE1 isoforms exhibit full thermal hysteresis (TH) activity, whereas the SP and QAE2 isoforms are incapable of preventing the growth of ice crystal. We determined the antifreeze activity of three isoforms, AFP8 (QAE1), AFP11 (QAE2), and AFP6 (SP),  of the Japanese notched-fin eelpout (Zoarces elongates Kner) AFPs and characterized the structural and dynamics properties of their ice-binding surface using NMR. We found that the AFP11, AFP6, and mutant AFP8 were incapable of stopping the growth of ice crystals and exhibited structural changes, as well as increased conformational flexibility, in the first 310 helix of the sequence. Our results suggest that the inactive nfeAFPs are incapable of anchoring water molecules due to the unusual and flexible backbone conformation of their primary prism plane-binding surface.


Session: Dynamics, poster number: 118
NMR Dynamics Study Reveals the Zα Domain of Human RNA Editing Enzyme ADAR1 More Slowly Binds to Z-RNA than Z-DNA
Ae-Ree Lee; Joon-Hwa Lee
Gyeongsang National University, Jinju, Korea, Republic of

  Human RNA editing enzyme ADAR1 deaminates adenine in pre-mRNA to yield inosine. The Zα domains of human ADAR1 (hZαADAR1) binds specifically to left-handed Z-RNA as well as Z-DNA and stabilizes the Z-conformation. To answer the question of how hZαADAR1 can induce both B–Z transition of DNA and A–Z transition of RNA, we investigated the structure and dynamics of hZαADAR1 in complexes with 6-bp Z-DNA or Z-RNA. We performed chemical shift perturbation and relaxation dispersion experiments of hZαADAR1 upon binding to Z-DNA as well as Z-RNA. Our study demonstrates the unique dynamic feature of hZαADAR1 during A–Z transition of RNA, in which the hZαADAR1 protein forms thermodynamically stable complex with Z-RNA like Z-DNA but kinetically more slowly converts to Z-RNA than Z-DNA. We also found the distinct structural features of the hZαADAR1 in the Z-RNA binding conformation. Our results suggest that the A–Z transition of RNA by hZαADAR1 displays the unique structural and dynamic feature that may be involved in targeting ADAR1 for a role in recognition of RNA substrates.


Session: Dynamics, poster number: 119
Liquid In Situ Electrochemical Nuclear Magnetic Resonance (EC-NMR) Spectroscopy to Study Electrochemical Processes
Shuo-Hui Cao; Xiao-Ping Zhang; Wen-Long Jiang; Zhong Chen
Xiamen University, Xiamen, China
Since the strength of nuclear magnetic resonance (NMR) to noninvasively realize the structural elucidation and quantitative analysis of small organic molecules, in principle, liquid in situ electrochemical NMR (EC-NMR) possesses great advantages for real-time investigation of electrochemically generated solution species. However, the intrinsic incompatibility between the coupling techniques, as well as the sophisticated setups modification still limit the effective applications in a wide range. To overcome these bottlenecks, herein we propose easy-to-construct designs, meanwhile with improved electrochemical and NMR performances. As proof of concepts, model experiments including redox reaction and alcohols electrooxidation are utilized to test the capacity of liquid in situ EC-NMR. This work demonstrates the universality and effectivity of the proposed platform to develop liquid in situ EC-NMR as a useful tool for the analysis of electrocatalytic dynamic processes at a molecular level.


References
[1] Y. J. Tong, Curr. Opin. Electrochem. 2017, 4, 60-68.
[2] S.-H. Cao, Z.-R. Ni, L. Huang, H.-J. Sun, B. Tang, L.-J. Lin, Y.-Q. Huang, Z.-Y. Zhou, S.-G. Sun, Z. Chen, Anal. Chem. 2017, 89, 3810-3813
[3] Z.-R. Ni, X.-H. Cui, S.-H. Cao, Z. Chen, AIP Adv. 2017, 7, 085205.
[4] Y.-Q. Huang, S.-H. Cao, Y. Yang, S.-H. Cai, H. Zhan, C.-H. Tan, L. Lin, Z.-Y. Zhang, Z. Chen, Anal. Chem. 2017, 89, 7115-7122.

Session: Dynamics, poster number: 120
Use of Magnetic Resonance Imaging (MRI) for Coating Characterization
Linlin Li
PPG Industries Inc., Allison Park, PA

There has been an increasing interest in using of Magnetic Resonance Imaging (MRI) for characterizing cured polymers or coatings. Compared with traditional NMR techniques (solution or solid NMR), MRI needs minimum sample preparation, and yet provides unique information about crosslinking density, polymer homogeneity and water penetration at different depth of the film or substrate. In this presentation, NMR Mouse (MObile Universal Surface Explorer) was used to study several coatings systems. For wood coatings, our work indicated that MRI is effective in measuring the coating penetration depth, but also in monitoring the moisture content in the substrate. In addition, the use of MRI for detecting crosslinking density for 3D-Printed parts and free polymer films will be also presented.


Session: Dynamics, poster number: 121
Carbon Dioxide Capture Materials and Dynamics
Robert M. Marti1; Joshua D. Howe2; Cody R. Morelock2; Colton M. Moran2; Jayraj N. Joshi2; Mark S. Conradi1; Krista S. Walton2; David S. Sholl2; Sophia E. Hayes1
1Washington University in Saint Louis, Saint Louis, MO; 2Georgia Institute of Technology, Atlanta, GA
Using in situ variable temperature NMR measurements, we can elucidate structural details of carbon dioxide inside the one-dimensional channels of Mg-MOF-74. Understanding dynamics is key to synthesizing better carbon dioxide adsorbents. In addition to gas dynamics, we studied a unique synthesis of MIL-53(Al) using 27Al NMR to track the solid-to-solid transformation of MIL-53(Al) from aluminum carbide.

Session: Dynamics, poster number: 122
Filtered NOESY and water-amide NOE to detect conformational differences in a protein complexed with highly analogous inhibitors
John Persons; Shahid Khan; Rieko Ishima
University of Pittsburgh, Pittsburgh, PA

In the era of state-of-the-art inhibitor design and high-resolution structural studies, detection of significant but small protein structural differences among inhibitor-bound forms is critical when developing potent inhibitors. Comparison of protein structures bound to highly analogous inhibitors has been mostly done using X-ray crystallographic analyses or MD simulations. Solution NMR spectroscopy is less explored for this purpose, presumably because protein NMR structures and dynamics among the “rigid” inhibitor bound forms are similar to one another. Here, we applied 3D 15N-half filtered NOESY experiments and 2D 15N-edited water-amide NOE experiments, in order to identify how a subtle changes in in a few chemical moieties of the inhibitors affect their interactions with HIV-1 protease. The work is supported by NIH GM109767.


Session: Dynamics, poster number: 123
Use of NMR to Understand Stability Issue for Azetidine Containing Compounds in Drug Discovery
Guoyun Bai1; Thomas O'Connell1; Matthew Brown2; Michael Brodney2; Christopher Butler2; Lara Czabaniuk1; Adam Gilbert1; Erik LaChapelle1; Chao Li1; Laura McAllister2; Laurence Philippe1; Romelia Salomon Ferrer1; Kevin Ogilvie1; Michael Shapiro3; Daniel Uccello1; Jane Withka1; Jiangli Yan4
1Pfizer Inc, Groton, CT; 2Pfizer Inc, Cambridge, MA; 3Independent Scientist, East Lyme, CT; 4MassBiologics, Boston, MA

Due to poor chemical stability observed for a series of azetidine-containing compounds, we developed multiple NMR methods to enable the identification of more stable bioactive analogs.

Stability data at low pH was generated for a variety of analogs to gain a better understanding of the structure-activity relationship (SAR) associated with the observed decomposition. The structures of the degradants were characterized to help elucidate the mechanism of decomposition, which suggested the pKa of the azetidine nitrogen as a determining factor. Atomic level pKa measurement was achieved using multiple NMR methods. In addition, 15N chemical shift data also provided support for a developing trend of greater stability associated with conjugated aryl groups. This result enabled improved confidence in designing more stable analogs.


Session: Dynamics, poster number: 124
Interaction of Huntingtin Exon-1 peptides with lipid-based micellar nanoparticles probed by solution NMR and Q-band pulsed EPR
Alberto Ceccon1; Thomas Schmidt1; Vitali Tugarinov1; Samuel Kotler1; Charles Schwieters2; Marius Clore1
1LCP, NIDDK, NIH, Bethesda, MD; 2ISL, CIT, NIH, Bethesda, MD
Huntington’s disease is a fatal neurodegenerative disease arising from the presence of more than 35 CAG repeats within exon 1 of the Huntingtin (htt) gene, resulting in expansion of the polyQ domain that lies immediately downstream of the 16-residue-N-terminal sequence (httNT). We have characterized the interaction of two such peptides, httNTQ7 and httNTQ10 with lipid micelles as membrane-mimic using NMR chemical-exchange-saturation-transfer (CEST), circular-dichroism and pulsed-Q-band EPR. Exchange between free and micelle-bound peptides occurs on the millisecond time scale with a Kd ~ 0.5-1 mM. Pulsed Q-band EPR shows that a monomer-dimer equilibrium exists on the surface of the micelles and that the two helices of the dimer adopt a parallel orientation, thereby bringing two disordered polyQ tails into close proximity.

Session: Dynamics, poster number: 125
Effect of Solvent Deuteration upon Nuclear and Electronic Spin-Lattice Relaxation Times
Christopher Parish1; Peter Niedbalski2; Qing Wang1; Lloyd Lumata1; Likai Song3
1University of Texas at Dallas, Richardson, TX; 2Center for Pulmonary Imaging Research, Cincinnati, OH; 3National High Magnetic Field Laboratory, Tallahassee, FL
Deuteration of one’s glassing solvent is often used in 13C dynamic nuclear polarization (DNP) to improve the resulting nuclear magnetic resonance (NMR) signal. Yet, the mechanism behind this boost is poorly understood. In an effort to acquire some insight to this conundrum, this study examined the effect of solvent deuteration upon 13C and electronic spin-lattice relaxation times of eight solutions containing 2-3 M [1-13C] acetate at 3.35 T and 1.2 K. This group of eight samples were separated into groups of two so that the effect of solvent deuteration could be examined when the radical or glassing matrix were varied. These results were discussed in light of the thermal mixing model of DNP.

Session: Dynamics, poster number: 126
13C Dynamic Nuclear Polarization using BDPA and trityl OX063
Christopher Parish1; Peter Niedbalski2; Andhika Kiswandhi3; Qing Wang1; Fatemeh Khashami1; Lloyd Lumata1
1University of Texas at Dallas, Richardson, TX; 2Center for Pulmonary Imaging Research, Cincinnati, OH; 3Department of Chemistry, Kyoto University, Kyoto, Japan

There has been much recent effort to optimize 13C dynamic nuclear polarization (DNP) at low temperatures and within high magnetic fields. This has been largely motivated by the 2003 invention of dissolution DNP which nets liquid-state samples with nuclear magnetic resonance (NMR) signals enhanced by several thousand-fold. Past research suggests that studies on biradicals and on radical mixtures could improve the current understanding of the physics behind DNP. With this goal in mind, our study examined 13C DNP performed using a 1:1 v/v 13C acetic acid/sulfolane solution doped with a 1:1 mixture of two narrow linewidth free radicals: trityl OX063 (trityl) and BDPA. The results were discussed from the viewpoints of spin diffusion and thermal mixing.


Session: Dynamics, poster number: 127
Temperature Dependence of Proton NMR Relaxation Times at Earth’s Magnetic Field
Fatemeh Khashami1; Peter Niedbalski2; Christopher Parish1; David Clark1; Qing Wang1; Lloyd Lumata1
1The University of Texas at Dallas, Dallas, TX; 2Center for Pulmonary Imaging Research, Cincinnati, Cincinnati, OH, USA
The earth’s magnetic field is highly uniform which is required for high-resolution nuclear magnetic resonance (NMR) spectroscopy. Here, we have investigated the spin-lattice relaxation time (T1) of water-glycerol mixtures at earth's magnetic field (1700 Hz).The water proton T1s at different ratios of water-glycerol contents were measured at different temperatures ranging from -20 oC to 90 oC. The water proton T1 increases linearly with temperature, from ~2 s at 20 °C to ~6.6 s at 78.9 °C. However, the presence of glycerol content as a mixture results in a decrease in the slope of this linear relationship and, for high glycerol content, the linearity of this behavior at low temperatures is disrupted. These results are discussed under the Bloembergen-Pound-Purcell (BPP) theory.

Session: Dynamics, poster number: 128
NMR Study of the Catalytic Activity towards Phosphate Ester Hydrolysis between Multinuclear Complexes Formed by Different Binding Group
Zongyao Zhang
Renmin University of China, Beijing, China
In this work, we present study on the mechanism of the hydrolysis of phosphate catalysed by different multinuclear complexes, monitored by a combination of NMR and other analytical methods.

Session: Dynamics, poster number: 129
MAS-DNP NMR investigations on the transient intermediate states of melittin by the rapidly mixing and freezing technique
Jaekyun Jeon
National Institutes of Health, Bethesda, MD
Characterization of the protein folding intermediates is crucial, as the intermediates can reveal the fundamentals of folding transitions including the disease-related misfolding cases. However, the transient and statistically lowly populated characters of such states make the structural analysis very challenging. In this study, we have developed the microfluidic rapid mixer and freezer system that can trap intermediate states with 1-2 millisecond time resolution like taking snapshots, and the MAS-DNP technique at very low temperature (25 K) was applied to overcome the intrinsically low signal-to-noise from such intermediate species. As an initial system, the protein folding along the simultaneous tetramerization of a small bee venom peptide, melittin, is investigated, and the results will be discussed.

Session: Dynamics, poster number: 130
NMR Spin Diffusion and Cryoporometry Study of Microheterogeneity in PEG-based Polyacrylate Gel
Bing Wu1, 2; Daniel Hermida-Merino2; Andreas Heise1
1Royal College of Surgeons in Ireland, Dublin, Ireland; 2European Synchrotron Radiation Facility, Grenoble, France
In order to satisfy the demand for this type of materials, among all the manufacturing techniques, UV-curing is the most common approach used by people to produce these polyacrylates in a large scale. However, the rather uncontrollable radical polymerization often results in a heterogeneous product with complicated morphological properties. Meanwhile, the addition of monoacrylates into the formulation, like in most commercial polyacrylate products, further convolutes the morphological and mechanical understanding of their physical properties in terms of its microstructural interpretation. In this study, we focused on using NMR spin diffusion and NMR cryoporometry to probe the ‘nanogel’ formation during the curing procedure.

Session: Dynamics, poster number: 131
Toward Cleavable Metabolic / pH Sensing “Double Agents” Hyperpolarized via NMR Signal Amplification by Reversible Exchange
Jamil A. Mashni1; Bryce E. Kidd1; Miranda N. Limbach1; Fan Shi1; Eduard Y. Chekmenev2; Yuqing Hou1; Boyd M. Goodson1
1Southern Illinois University, Carbondale, IL; 2Wayne State University, Detroit, MI
The ability of magnetic resonance to spectrally discriminate among different biochemical states makes MRI an attractive modality for molecular imaging but suffers from low detection sensitivity. Hyperpolarization methods aim to combat this, thus opening the door to detect low concentration species. Hyperpolarization of spin-labeled carboxylic acids and their derivatives, have been of particular interest because they can provide enhanced MR signals from metabolites in vivo (e.g. Kreb cycle intermediates). Through SABRE-SHEATH, transfer of spin order from parahydrogen to acetylimidazole 15N atoms to the acetyl 13C site of 1-13C-15N2-acetylimidazole occurs, giving rise to relatively long hyperpolarization lifetimes at 0.3 T. Immediately following polarization transfer, the 13C-labeled acetyl group is hydrolytically cleaved to produce hyperpolarized 13C-acetate/acetic acid and 15N2-imidazole.

Session: Dynamics, poster number: 132
Transport Properties of Crystals of Zeolitic Imidazole Framework-11 (ZIF-11) Embedded in Polymers to Form Mixed-Matrix Membranes
Evan Forman1; Amineh Baniani1; Lei Fan1; Kirk Ziegler1; Erkang Zhou2; Ryan Lively2; Sergey Vasenkov1
1University of Florida, Gainesville, FL; 2Georgia Institute of Technology, Atlanta, GA
Mixed-matrix membranes (MMMs) consisting of zeolitic imidazolate framework (ZIF) particles embedded in a polymer exhibit promising separation performance for gas mixtures that are difficult to separate. Detailed understanding of molecular diffusion inside ZIF particles located in MMMs is required to optimize transport properties of MMMs. Here we report that the diffusivity of ethylene inside ZIF particles for displacements much smaller than the particle size is influenced by the type of the polymer surrounding ZIF particles in MMMs. This observation is attributed to the ability of a polymer to restrict framework flexibility of embedded ZIF particles. The diffusion measurements were performed by 13C pulsed field gradient NMR, utilizing a high magnetic field and high magnetic field gradients.

Session: Dynamics, poster number: 133
An Experiment for Measurements of {15N}-H/D Solvent Exchange Rates of Arginine Side Chains
Harold W. Mackenzie; D. Flemming Hansen
ISMB, Univ. College London, London, United Kingdom
Arginine residues are imperative for many active sites and protein-interaction interfaces because the guanidinium group has five possible hydrogen-bond formation sites. An NMR method is presented to quantify the solvent exchange rates of arginine side chains to characterise the strength of possible interactions. The method employs 13C-detection and utilises the one-bond 15N deuterium isotope shift to generate two exchanging resonances in H2O/D2O mixtures. Applications to arginine side chains in T4 Lysozyme will be shown, where there is a good correlation between the solvent exchange rates obtained and the interactions observed in the crystal structure. It is envisaged that the new method serves as a particularly valuable tool to characterise active sites in enzymes, protein-protein or protein-nucleic acid interactions.

Session: Dynamics, poster number: 134
Solid-state NMR Investigation of Nucleosome Structure and Dynamics
Xiangyan Shi1; Chinmayi Prasanna1; Toshio Yamazaki2; Konstantin Pervushin1; Lars Nodenskiöld1
1Nanyang Technological University, Singapore, Singapore; 2RIKEN Center for Life Science Technologies, Yokohama City, Japan
DNA in eukaryotic cells is organized in nucleosomes formed by 145-147 bp DNA wrapping around histone octamer composed of four histone proteins. The structure and dynamics of histones play critical roles in genomic regulation. Recently, we implemented solid-state NMR (SSNMR) technique to investigate the structure and dynamics of histones in nucleosome core particle (NCP) and nucleosome array at the atomic level. The secondary structure was successfully determined for the globular domain of H4 in NCP. Site-specific dynamics of the histone were quantified, for the first time, which revealed diverse motions existing in the protein. Our study elucidated that H4 in nucleosome array present enhanced dynamics in several regions in comparison with these in the tightly packed columnar hexagonal NCP assemblies.

Session: Dynamics, poster number: 135
Investigation of Transfer Mechanisms in Dynamic Nuclear Polarization (DNP) 13C Direct Excitation Experiments on non-ionic Surfactants
Sarah Bothe1; Markus M. Hoffmann2; Torsten Gutmann1; Gerd Buntkowsky1
1Technische Universität Darmstadt, Darmstadt, Germany; 2The College at Brockport, Brockport, New York
A study of Dynamic Nuclear Polarization (DNP) is presented, where interestingly two superimposed and 180° phase shifted resonance sets, were obtained in the DNP enhanced 13C Magic Angle Spinning (MAS) spectra for different systems. These sets originate from a direct polarization transfer mechanism, which is commonly known for 13C MAS experiments and an unexpected indirect polarization transfer mechanism via the proton spin pool. An analysis of the mechanisms responsible for these sets of resonances will be presented in detail for the radical AMUPol dissolved in the surfactant solution of C10E6. This analysis is highly important for all future applications of direct 13C MAS DNP.

Session: Dynamics, poster number: 136
NMR Studies of Loaded Microspheres
Ming Huang1; Sisi Chen2; Rex Gerald II3; Jie Huang1; Klaus Woelk1
1Missouri University of Science & Technology, Rolla, MO; 2Brewer Science, Rolla, MO. ,USA; 3American Inventor Institute, Willow Spring, IL,USA
Three 1H NMR studies were conducted to demonstrate the applicability of NMR spectroscopy for the characterization of PWHGMs as drug carriers. The first two studies showed NMR evidence of loaded n-dodecane and chloroform inside the microspheres. NMR peaks of the loaded materials could be distinguished from the peaks of the materials in the surrounding solution. A third study used the hydrolysis of isopropyl acetate to show that material from the inside of the microspheres exchanged with the surrounding environment. The formation of isopropanol was the indicator for exchange of isopropyl acetate in the microspheres and concentrated H2SO4 in the surrounding solution. These NMR results for the first time provided both static and dynamic information of loaded materials in the microspheres.

Session: Dynamics, poster number: 137
Battery electrolytes – Multi-nuclear Fast Field Cycling relaxometry reveals important molecular dynamics information
Danuta Kruk1; Małgorzata Florek-Wojciechowska1; Oscar Tutusaus2; Gianni Ferrante3; Moreno Pasin3; Rebecca Steele3
1University of Warmia and Mazury in Olsztyn, Olsztyn, Poland; 2Toyota Research Institute of North America, Ann Arbor, MI; 3Stelar s.r.l., Mede (Pv), Italy
The growing need of electric energy required to power portable electronic devices and electric vehicles promote an increasing interest in research on high-performance new batteries. In this study we consider two electrolytes: bis(trifluoromethane)sulfonimide lithium salt (C2F6LiNO4S2) and lithium phosphorus sulfide (Li3PS4). We use Fast Field Cycling relaxometry to characterize their molecular dynamics, on 1H, 19F, 7Li and 31P nuclei, from 5 kHz up to 30 MHz, and over a wide temperature range. We show how to obtain dynamics parameters for different nuclei from the experimental data (NMRD profiles) and basic theoretical information: the self-diffusion coefficient, the relative diffusion coefficient (correlation of ionic dynamics), as well as correlation times (rotational dynamics) and information about the presence of clusters and their size.

Session: Dynamics, poster number: 138
Measuring and Modeling Nuclear Spin Temperature in Strained GaAs Using 75As OPNMR
Michael West
Washington University, St Louis, MO
Various methods have been developed to achieve high nuclear spin polarization in order to study NMR-insensitive nuclei by NMR.  One technique, optically pumped NMR (OPNMR), uses laser excitation of a semiconductor's band structure to produce hyperpolarized electrons, and therefore the nuclei mediated by the Fermi contact hyperfine interaction.  Here we show a special case in strained GaAs where the nuclear spin temperature (and therefore polarization) can be directly calculated from a single NMR spectrum based on density matrix formalism models for both Bloch nutation and quadrupolar echo pulse sequence techniques. 

Session: Dynamics, poster number: 139
Relaxation-based NMR reveals early self-association and misfolding events of huntingtin N-terminal peptide fragments
Samuel Kotler; Vitali Tugarinov; Alberto Ceccon; David Libich; Charles Schwieters; Marius Clore
National Institutes of Health, Bethesda, MD
Huntington’s disease (HD) is a heritable neurological disorder deriving from genetic expansion of a polyglutamine (polyQ) sequence in the huntingtin protein. Our knowledge of how and why an expanded tract of polyQ leads to the formation of amyloid in HD is largely hampered by little high-resolution structural and dynamic insight into this process. Using relaxation-based NMR, we found that N-terminal huntingtin fragments have a concentration-dependent effect on the formation of early oligomeric species. Additionally, while the polyQ sequence is necessary for monomer-to-oligomer association, the N-terminal amino acids of the huntingtin peptide fragment drive this kinetic process. Early self-association of N-terminal huntingtin may highlight the events that trigger the onset of huntingtin aggregation into amyloid fibrils.

Session: Dynamics, poster number: 140
Understanding Response Mechanisms of Post-translational Phosphorylation in Signaling Proteins
Brendan Mahoney; Jeffrey Peng
University of Notre Dame, Notre Dame, IN
Cell-signaling proteins often have their function modulated via post-translational phosphorylation of serines, threonines, or tyrosines. These perturb the structure and dynamics to promote long-range allosteric changes. Through solution NMR studies of our model protein human Pin1, we highlight basic biophysical principles governing phosphorylation-induced allostery. Pin1’s modification sites are hotspots surrounded by conserved electrostatic networks, enabling intramolecular feedback. The phosphorylation sites exploit conserved motifs and pathways. Arginine residues surround three phosphosites we have studied, and their side chain Nϵ-Hϵ groups provide insight into the electrostatic effects when modification is near Pin1’s catalytic site or its interdomain interface. Unifying features suggest that pre-existing electrostatics form the foundation for intramolecular phosphorylation responses.

Session: Dynamics, poster number: 141
Solid-State NMR of Highly 13C- Enriched Cholesterol in Lipid Bilayers
Lisa Della Ripa; Zoe Petros; Alexander Cioffi; Dennis Piehl; Joseph Courtney; Martin Burke; Chad Rienstra
University of Illinois at Urbana-Champaign, Urbana, IL
Cholesterol (Chol) is essential to a myriad of biochemical and biophysical processes, making atomistic details of Chol’s interactions with phospholipids and proteins of fundamental interest. We describe a method for examining the structure and dynamics of Chol in lipid bilayers using high levels of 13C enrichment in combination with magic-angle spinning (MAS). We quantify the levels of 13C incorporation and demonstrate high sensitivity and resolution in 2D 13C-13C and 1H-13C spectra, enabling de novo assignments and site-resolved order parameter measurements. These experiments were obtained in a fraction of the time required for natural abundance sterols. We envision that 13C-enriched Chol will be useful for a variety of SSNMR studies to examine structure, dynamics and interactions with membrane proteins and drugs.

Session: Dynamics, poster number: 142
NMR Dynamics Reveals Allostery in Ubiquitination => HARD and Geometric Approximation
Kalyan Chakrabarti2; Fa-An Chao1; Jess Li1; Domarin Khago1; Allan Weissman1; Ranabir Das3; R. Andrew Byrd1
1National Cancer Institute, Frederick, MD; 2Max Planck Institute for Biophysical Chemistry, Göttingen, Germany; 3National Center for Biological Sciences, Bangalore, India
Many biological processes utilize the interplay of two or more proteins, driven by allosteric and dynamic changes. NMR, combined with other structural and biophysical techniques, is unique in the ability to dissect these interactions. However, these tools provide ground-state structures, while it is often the case that low-population excited states are key to the binding interactions. NMR dynamics methodology is expanding, such that both a wider range of rate processes and more complex exchange models can be analyzed (Chao & Byrd: JACS 2016, JMR 2017, Emerging Topics in Life Sciences 2018). We describe the application of CPMG, adiabatic R1rho, R2rho experiments, and geometric approximation to an E2 ubiquitin conjugating enzyme to illustrate the importance of sub-states along the reaction coordinate.

Session: Dynamics, poster number: 143
Parahydrogen Induced Polarization using Supported Pt Catalysts Prepared by Atomic Layer Deposition
Diana Choi1; Bochuan Song2; Tommy Yunpu Zhao1; Yong Du1; Helena Hagelin-Weaver2; Clifford R. Bowers1
1University of Florida, Chemistry, Gainesville, FL; 2University of Florida, Chemical Engineering, Gainesville, FL
Atomic Layer Deposition (ALD) is a proven tool for the large-scale synthesis of supported metal nanoparticle catalysts with precisely controlled particles sizes using sequential and self-limiting surface reactions. ALD can be used to prepare single metal atom catalysts or clusters as well as bimetallic catalysts. In this project, ALD was employed to prepare atomically precise catalysts using a NanoSolutionsTM rotary bed ALD reactor system. This system is designed for powder coating using ALD and is therefore well-suited for catalyst synthesis. The catalysts were characterized using temperature programmed reduction, CO chemisorption, and parahydrogen induced polarization (PHIP) NMR spectroscopy. Preliminary results will be reported in this poster.

Session: Dynamics, poster number: 144
Diffusion of light gases in nanoporous gold by pulsed field gradient NMR at high field
Amineh Baniani1; Evan Forman1; Marcus Bäumer2; Sergey Vasenkov1
1University of Florida, Gainesville, FLORIDA; 2University of Bremen, Bremen, Germany
Nanoporous gold is a promising catalyst for oxidation of carbon monoxide to carbon dioxide. Detailed understanding of molecular diffusion in this material is of importance for its potential application in catalysis. Here, we report first microscopic study of gas diffusion in nanoporous gold for a broad range of displacements, smaller and larger than the relevant dimension of nanoporous gold particles. The diffusion measurements were performed by 13C pulsed field gradient NMR for carbon monoxide, methane, and carbon dioxide, utilizing high magnetic field. These measurements allowed determining tortuosity factors, which were found to be the same for each studied sorbate, within uncertainty. The value of the tortuosity factor was found to be consistent with theoretical expectations based on the sample porosity.

Session: Dynamics, poster number: 145
An Examination of Existing and Emerging Safety Options for High-Pressure NMR
Susan Butch
Wilmad-Labglass, Vineland, NJ
Numerous research applications exist which require pressurization of NMR tubes, including protein folding, stability, and catalysis. Engineering formulas for cylinders <300 mm predict the pressure maximum of any rigid material to be: P(max) = (wall thickness/OD) x K(t), where OD and wall thickness are tube specifications and K(t) is an empirical tensile strength of the material. Though safety measures such as blast shields and safety boxes can be employed, the nature and fragility of glass make this an inherently hazardous undertaking. In addition, the existing safety precautions only protect researchers during sample preparation and do not follow though to transport and analysis. Herein, a new design for researcher protection during high-pressure NMR experiments will be detailed and discussed.

Session: Dynamics, poster number: 146
Facile Removal of Homogeneous SABRE Catalysts for Purifying Hyperpolarized Agents
Jonathan L. Gesiorski1; Bryce E. Kidd1; Max E. Gemeinhardt1; Roman V. Shchepin2; Kirill V. Kovtunov3; Igor V. Koptyug3; Eduard Y. Chekmenev4; Boyd M. Goodson1
1Southern Illinois University, Carbondale, IL; 2Vanderbilt University Institute of Imaging Science, Nashville, TN; 3International Tomography Center SB RAS, Novosibirsk, Russia; 4Department of Chemistry, Wayne State University, Detroit, MI
MRI is a useful imaging method due to its ability to distinguish boundaries of soft tissues and even discern among different biochemical species and physiological states, but suffers from low detection sensitivity. The generation of non-Boltzmann spin population distributions via hyperpolarization is thus gaining greater interest. We report record-high naturally abundant 15N polarization of 34% (>100k-fold enhancement at 9.4 T) for metronidazole via SABRE-SHEATH. We also demonstrate a simple route to remove homogenous Ir-based SABRE catalysts from solutions post-15N hyperpolarization via the addition of commercially available functionalized (3-mercaptopropyl and 2-mercaptoethyl ethyl sulfide) SiO2 particles, all while retaining significant levels of 15N polarization. Our results pave way for future studies involving in vivo imaging using SABRE- and/or SABRE-SHEATH-generated hyperpolarized agents.

Session: Dynamics, poster number: 147
Enhanced dynamic nuclear polarization via swept microwave frequency combs
Ashok Ajoy1; Kristina Liu1; Xudong Lv1; Raffi Nazaryan1; Guoqing Wang2; Emanual Druga1; Jeffrey Reimer3; Dieter Suter4; Chandrasekhar Ramanathan5; Carlos Meriles6; Alexander Pines1
1Department of Chemistry, UC Berkeley, Berkeley, California; 2Department of Physics, Peking University, Beijing, China; 3Dep. of Chemical Biomolecular Eng. UC Berkeley, Berkeley, CA; 4Fakultat Physiks, TU Dortmund, Dortmund, Germany; 5Dept. Physics and Astronomy, Dartmouth University, Hanover, New Hampshire; 6Dep. of Physics, CUNY, New York, New York
Dynamic Nuclear Polarization (DNP) has enabled enormous gains in magnetic resonance signals, and consequently has led to vastly accelerated NMR/MRI imaging and spectroscopy. Unlike conventional cw-techniques, DNP methods that exploit the full electron spectrum allow direct participation of all electrons in the hyperpolarization process but are often inefficient because the sweeps, constrained by adiabaticity requirements, are slow. In this work we develop a DNP technique in powdered microdiamonds at 70 T from 30 to 100 to overcome the DNP bottlenecks set by the slow sweeps, employing a swept microwave frequency comb that increases the effective number of polarization transfer events while respecting adiabaticity constraints. This allows a multiplicative gain in DNP enhancement, scaling with the number of comb frequencies. 

Session: Dynamics, poster number: 148
Probing Cs/131Xe versus Rb/131Xe Spin Exchange Using in situ Hyperpolarized 131Xe NMR
Michael J. Molway1; Bryce E. Kidd1; Liana Bales1; Megan N. Murphy1; Dustin Basler1; Kierstyn Albin1; Michael J. Barlow2; Eduard Y. Chekmenev3; Boyd M. Goodson1
1Southern Illinois University, Carbondale, IL; 2University of Nottingham, Nottingham, United Kingdom; 3Wayne State University & Karmanos Cancer Center, Detroit, MI
Spin-exchange optical pumping allows for the hyperpolarization of noble gases for applications in fundamental physics. While difficult to hyperpolarize, 131Xe has potential applications as a HP nuclear target for probing time-reversal invariance violations. Our interests lie in optimizing the polarization of 131Xe during stopped-flow SEOP at higher Xe densities, as a function of AM choice (Rb vs. Cs), temperature, and light source. In the present work, batches of enriched (~84%) 131Xe/N2 were illuminated with circularly polarized laser of varying output power. Build-up time constants were determined from 131Xe signal growth at several temperatures, monitored via in situ low-field NMR. Extraction of polarization values and spin-exchange rates for 131Xe/Cs versus 131Xe/Rb (and comparison with 129Xe) is the subject of ongoing work.

Session: Dynamics, poster number: 149
29Si NMR at Gigapascal Pressures
Corey Pilgrim; Christopher Colla; Gerardo Ochoa; Jeffrey Walton; William Casey
University of California, Davis, Davis, CA
Combining high-pressure clamp cells with a simple tank circuit design has allowed confirmation of theoretical geochemical models. However, obtaining high-resolution spectra using superconducting magnet systems is difficult due to the relative insensitivity of high-pressure NMR probes to conventional shimming. With this in mind, we have designed a new probe to fit in a narrow-bore superconducting magnet to reduce the amount of metal in the probe. This new probe is also coupled with a custom-built high-power shim stack provided by Resonance Research, Inc. that allows up to 5A of current on each shim channel. Herein, we present 29Si data at high enough resolution to investigate the complexation and oligomerization of aqueous silicate at geochemically relevant conditions (up to 1.8 GPa).

Session: Dynamics, poster number: 150
Improvements in Characterization of Discrete State Dynamics from Residual Dipolar Couplings
Casey Cole1; Gaetano Montelione2; Homayoun Valafar1
1University of South Carolina, Columbia, South Carolina; 2Rutgers University, Piscataway, NJ
Mounting evidence the importance of internal dynamics of molecules in their enzymatic and biological functions. Therefore, the development of rapid, cost-effective, and unbiased methods to aid in these studies becomes critical in the treatment of many diseases. In our previous work, we presented a strategy for structure calculation and reconstruction of discrete state dynamics from RDC data utilizing the REDCRAFT software package. Based on our investigations, with ±1Hz of error added, arc motions with more than 30° of rotation are recognized and reconstructed with sufficient accuracy. To further the sensitivity of our method and to explore more challenging motions we have proposed and investigated a new method that fuses our previous method with concepts from replica-averaged molecular dynamic simulations.

Session: Dynamics, poster number: 151
DIPDAP – A Pulse Programming Concept for Considering the Effects of Spin-Spin and Spin-Lattice Relaxation during Frequency-selective Adiabatic HS1 Pulses
Annalise Pfaff; Klaus Woelk
Missouri S&T, Rolla, MO
Adiabatic full passages are often used to achieve uniform and B1-insensitive inversion of magnetization across a well-defined range of NMR frequencies. To accomplish inversions with narrow frequency ranges (< 100 Hz), the duration of the adiabatic pulses can become quite long (> 500 ms), and T1 and T2 relaxation during the pulses may no longer be negligible. A new substitution concept (DIPDAP = Delay-Inversion Pulse-Delay for Adiabatic Pulse) is introduced that allows the pulse programmer to include the time frame of HS1 pulses into NMR sequences while accurately accounting for the effects of T1 and T2 relaxation. The DIPDAP concept is tested and verified with the multiple inversion-nulling solvent-suppression sequence EXCEPT.

Session: Dynamics, poster number: 152
Elucidating the Lipid Fusion Mechanism of Surfactant Protein B1-25 with Solution and Solid State NMR
Nhi Tran1; Gail E. Fanucci1; Joanna R. Long2
1Dept. of Chemistry, UF, Gainesville, Fl; 2Dept. of Biochemistry and Molecular Biology, UF, Gainesville, FL

We utilize solution and solid state NMR to characterize the lipid trafficking and lipid fusion mechanism of surfactant protein B1-25. The N-terminal 25 amino acid residues of pulmonary surfactant (PS) protein B (SP-B1-25) promotes rapid transit of lipids between lamellae in model PS lipid systems. This allows for surface tension reduction in the alveoli, and consequently renders SP-B the only pulmonary surfactant protein required for survival. Our ssNMR 2H and 31P results reveal SP-B1-25 induces a cubic lipid phase at physiologic temperature (37 °C) and promotes thermal stability through lipid interdigitation. With solution NMR, we aim to characterize the dynamics, membrane partitioning and structure of SP-B1-25, with a focus on the highly dynamic lipid anchoring (SP-B1-7) region.


Session: Dynamics, poster number: 153
General expressions for Carr-Purcell-Meiboom-Gill relaxation dispersion for N-site chemical exchange
Hans Koss1; Mark Rance2; Arthur G Palmer1
1Columbia University, New York, NY; 2University of Cincinnati, Cincinnati, OH
The Carr-Purcell-Meiboom-Gill (CPMG) experiment is widely used to characterize chemical exchange phenomena in biological macromolecules. Theoretical descriptions for 2-site exchange valid for all time scales are well-known as are descriptions of N-site exchange in the fast limit.
We recently have published new general N-site approximations for R experiments. Herein, we obtain general expressions for CPMG experiments for any N-site scheme and all experimentally accessible time scales. The most comprehensive expressions are complex, but can be used in efficient curve-fitting algorithms. For sufficiently slow chemical exchange, we obtain closed-form expressions, including compact expressions for 2-site, linear 3-site and triangular exchange. Furthermore, we highlight features that qualitatively characterize CPMG curves obtained from systems in various N-site exchange situations.

Session: Dynamics, poster number: 154
Beyond discrete time crystal signatures: hidden coherence, causes of decay, and the first ‘discrete time crystal echo’

Jared Rovny; Robert Blum; Sean Barrett
Yale University Physics Dept., New Haven, CT
The discrete time crystal (DTC) is a robust phase of a driven quantum system, whose key signature is a response at twice the drive period, even for imperfect driving. Two experiments recently demonstrated this signature (in trapped ions and diamond NV centers), where an open question is the cause for the decay of the response. We have shown this signature in an NMR system of 31P spins on a crystal lattice, and here we report two key results. First, we show evidence that the decay is substantially a coherent effect, by showing echoes from a novel “DTC echo” sequence. Second, we demonstrate that the action of the internal Hamiltonian during the pulse also plays an important role in the decay.

Session: Dynamics, poster number: 155
NMR observations of discrete time crystalline signatures in an ordered crystal of ammonium dihydrogen phosphate
Jared Rovny; Robert Blum; Sean Barrett
Yale University Physics Dept., New Haven, CT
The discrete time crystal (DTC) is an exotic phase of driven quantum systems which breaks the discrete time translation symmetry of its driving Hamiltonian. If the driving Hamiltonian has period T, the key signature of a DTC is a response with period 2T, which is robust to pulse angle variation. Two experiments (in trapped ions and diamond NV centers) recently demonstrated this signature. Here, we show signatures of DTC order in an NMR system of 31P spins in an oriented crystal of ammonium dihydrogen phosphate. Compared to the earlier experiments, we observe robust DTC oscillations across a much greater range of parameter space. We will describe how these DTC experiments are both similar to, and different from, familiar NMR sequences. 

Session: Dynamics, poster number: 156
Conformational dynamics of E. Coli Ribonuclease H
James Martin; Arthur Palmer
Columbia University, Manhattan, New York
Ribonuclease H is a non-sequence-specific endonuclease present in all branches of life. NMR Spectroscopy and Molecular Dynamic simulations indicate that ecRNH  populates an open state at room temperature, while ttRNH populates a closed state; as temperature increases, the populations trend towards equality, as expected from the Boltzmann equation. MD simulations and computational analysis of these proteins uncovered a mutation, V98A, which raises the Michaelis constant for ecRNH, thus giving it ttRNH-like properties. It is suspected that the alanine mutation at position 98 disallows a neighboring valine, V101, from interacting with it in a way that stabilizes the “closed” conformation. The disappearance and shift of V101 rotamer population distributions in V98A ecRNH MD trajectories compared to Wt trajectories support this claim

Session: Dynamics, poster number: 157
Exploring Optically Pumped NMR in Dilute Magnetic Semiconductor thin films: Ga1-xMnxAs
John Tokarski III1; Brenden Magill2; Chris Stanton1; Giti Khodaparast2; Clifford R Bowers1
1University of Florida, Gainesville, FL; 2Virginia Institute of Technology, Blacksburg, VA
Gallium-71 optically pumped NMR (OPNMR) measurements were performed on thin films of the dilute magnetic semiconductor Ga1-xMnxAs (where x= 0, 0.01, 0.03), a candidate material for spin-based devices and electronics. Films were grown by low-temperature molecular beam epitaxy (LT-MBE) on bulk GaAs substrate. OPNMR action spectra were collected as a function of photon energy using circularly polarized light. Moreover, for x=0.03, the NMR signal intensity was largely insensitive to photon energy and the helicity of incident light, consistent with light-induced quadrupolar relaxation. The effects of Mn on the spin dynamics was investigated by varying laser power and optical irradiation time.

Session: Dynamics, poster number: 158
Analysis of NMR Spin Relaxation Data Using an Inverse Gaussian Distribution Function
Andrew Hsu1; Fabien Ferrage2; Arthur G Palmer1
1Columbia University, New York, NY; 2CNRS - Ecole Normale Superieure, Paris, N/A
Spin relaxation in solution-state NMR spectroscopy is a powerful approach to explore the conformational dynamics of biological macromolecules. In the present work, the inverse Gaussian probability distribution function is derived from general properties of spectral density functions at low and high frequencies, utilizing the principle of maximum entropy. This is used to calculate the correlation and the spectral density function, using the model-free ansatz. To validate the approach, 15N spin relaxation data for the bZip domain of the S. cerevisiae protein GCN4 without cognate DNA were analyzed, and the quality of fits were better than for the extended model-free formalism, with additional degrees of freedom. The results extend previous models for the conformational dynamics of the bZip domain.

Session: Dynamics, poster number: 159
NMR pH Measurements using the 19F Chemical Shift of Fluoro-hydroxymethylpyridines
With and Without Deuterium Field-Frequency Lock

Ming Huang; Kaysi Lee; Klaus Woelk
Missouri S&T, Rolla, MO
Chemical-shift information has long been used to determine the pH of aqueous solutions. Especially 19F  shows great potential because of its high NMR sensitivity, its wide chemical-shift range, and its large chemical-shift response to the solution’s environment. Several water-soluble fluoro-hydroxypyridine and fluoro-hydroxymethylpyridine compounds were examined to find the maximum 19F chemical-shift dependence on pH. However, the investigations not only showed a chemical-shift dependence of the 19F signal but indirectly also a chemical-shift dependence of the lock solvent D2O on the pH. Spectra recorded with deuterium field-frequency lock exhibit a different 19F chemical-shift dependency compared to spectra recorded without the lock. The findings are supported by the 19F signals of an independent, external standard obtained from a trifluoroacetic acid CapPackTM.

Session: Dynamics, poster number: 160
On demand 13C hyperpolarization sign reversals in diamond
Xudong Lv1; Ashok Ajoy1; Guoqing Wang1, 2; Raffi Nazaryan1; Kristina Liu1; Emanual Druga1; Carlos Meriles3; Chandrasekhar Ramanathan4; Jeffrey Reimer5; Dieter Suter6; Alexander Pines1
1Department of Chemistry, UC Berkeley, Berkeley, CA; 2Peking University, Beijing, China; 3Dep. of Physics, CUNY, New York, NY; 4Dep. Physics and Astronomy, Dartmouth University, Hanover, NH; 5Dep. of Chemical Biomolecular Eng. UC Berkeley, Berkeley, CA; 6Fakultat Physiks, TU Dortmund, Dortmund, Germany

Diamond with extraordinary mechanical, electrical and thermal properties has attracted much attention, particularly the negatively charged nitrogen vacancy color center (NV-) defect in diamond with easy initialization and readout via optical pumping showed its potential in quantum information, quantum sensing and hyperpolarization. A room temperature optical hyperpolarization method in the low field regime in diamond was proposed [1] and in this study, we explored a striking feature of the method – a controllably linear hyperpolarization sign dependence.


Session: Dynamics, poster number: 161
Multiexponential T2 Relaxometry Analysis Based on a New Denoising and Modified MDL/Matrix Pencil Algorithms
Santi Ponte1; Maria Victoria Silva Elipe2; Stanislav Sykora3; Ester Maria Vasini3; Vadim Zorin1; Carlos Cobas1
1Mestrelab, Santiago De Compostela, Spain; 2Amgen, Thousand Oaks, CA; 3Mestrelab/Extra Byte, Castano Primo, Italy
Multiexponential relaxometry data analysis estimates the number of exponential components and their corresponding amplitudes and decay rates in experimentally recorded relaxation decays. A number of the components is often assumed to be discreet. The analysis is often complicated by the presence of the experimental noise. In this work we propose a new technique for decomposing a signal modelled as a sum of exponential decays into its components. The method is based on a new denoising algorithm for data preparation and modified MDL+Matrix Pencil for determination of the exponential components. The procedure does not require any prior estimates of the number of components present.




Session: Dynamics, poster number: 162
Determination of Exchange Coupling in AMUPOL Towards Efficient MAS DNP
Kan Tagami; A Equibal; Song-I Han
UC Santa Barbara, Santa Barbara, CA
Cross Effect (CE) Dynamic Nuclear Polarization (DNP) under magic angle spinning is heavily dependent on the interaction between two electrons; the dipolar (D) and exchange (J) couplings. Until recently only the dipolar coupling has been considered for determination of DNP enhancement. To accurately determine the exchange coupling in the DNP biradical AMUPol we used a combination of variable temperature solution state CW X-band EPR in various solvents and EasySpin simulations. We find that the value of J is temperature dependent, suggesting a thermally regulated equilibrium of exchange couplings. This is supported by comparison to the temperature dependence of TOTAPOL and DFT calculations of truncated biradicals; indicating that J coupling in AMUPol spans a wider distribution than previously assumed.