Session MOE. There are 5 abstracts in this session.

Session: HYPERPOLARIZATION 1, time: 4:00 - 4:25 pm

LED-Enhanced Fast-pulsing NMR: a Convenient and Inexpensive Approach to Increase NMR Sensitivity

Silvia Cavagnero
University of Wisconsin-Madison, Madison, WI

Low-concentration photochemically induced dynamic nuclear polarization (LC-photo-CIDNP) enables rapid analysis of amino acids and proteins in solution at nanomolar concentration. However, adoption of this hyperpolarization technology has typically been limited by the need for high-power lasers or other sophisticated light sources. Here, we present a variation of LC-photo-CIDNP employing inexpensive light-emitting diodes (LEDs). LED-enhanced NMR is as sensitive as laser-mediated LC-photo-CIDNP at only 1/1,000 of the cost. LED-enhanced NMR was then combined with new pulse sequences employing minimalist relaxation delays, leading to significantly shorter experimental times (> 2,000-fold) than conventional NMR. All the above technologies in combination with reductive radical quenchers enabled collecting 1D and 2D 1H-13C correlation data on sub-micromolar amino acids and proteins in only a few seconds.

Session: HYPERPOLARIZATION 1, time: 4:25 - 4:50 pm

Para-Hydrogen Induced Polarization – Production of highly concentrated metabolites and long polarization storage over 10s of minutes

Stefan Gloeggler
Max-Planck Institute for Biophysical Chemistry, Göttingen, Germany

Nuclear magnetic resonance (NMR) comes with the drawback of inherently low sensitivity. In order to improve detection sensitivity and enhance signals of certain compounds, hyperpolarization techniques have been developed.[1-6] Among these methods, para-hydrogen induced polarization (PHIP) is a rapid approach that generates hyperpolarized molecules within seconds.[3] At the conference, I am going to present the most recent advances that have enabled us to generate highly concentrated (50 mM) solutions of metabolites and their precursors (P13C > 50%) with particular applicability for in vivo experiments in the future.[6-9] Furthermore, we show our recent progress in designing and polarizing a library of 15N-enriched compounds in which the hyperpolarized signal can be stored for 10s of minutes.[10,11]

Session: HYPERPOLARIZATION 1, time: 4:50 - 5:05 pm

Advances towards microscale NMR with Parahydrogen

Sören Lehmkuhl1; Patrick TomHon1; Evan Akeroyd1; Austin Browning1; Bernhard Blümich2; Stephan Appelt2, 3; Thomas Theis1
1NC State University, Raleigh, NC; 2RWTH Aachen University, Aachen, Germany; 3Forschungszentrum Jülich, Jülich, Germany

SABRE (Signal Amplification By Reversible Exchange) is a parahydrogen based hyperpolarization technique, which allows for rapid, affordable and repeated hyperpolarization of molecules directly in room temperature solutions. For detection of the hyperpolarization we envision microscale sensors for applications, ranging from biomedical to high precision measurements.

We built small, inexpensive and portable “Paracubes” for parahydrogen generation, applied a modular immobilization system to yield a new class of heterogeneous hyperpolarization catalysts, engineered membrane reactors for continuous flow polarization, build a simple pneumatic shuttle to efficiently polarize and detect various nuclei at different magnetic fields, hyperpolarized of a variety of drugs and water, established low-field rare spin spectroscopy, simulated the SABRE dynamics and employed masing effects, ideal for ultra-high precision measurements.

Session: HYPERPOLARIZATION 1, time: 5:05 - 5:20 pm

Sensitivity Improvement using Adiabatic Solid Effect and Electron Decoupling with Pulsed Microwave Devices

Kong Ooi Tan1; Ralph Weber2; Robert Griffin1
1MIT, Cambridge, MA; 2Bruker BioSpin Corporation, Billerica, MA

The solid effect (SE) is a dynamic nuclear polarization (DNP) technique that mediates the polarization transfer from unpaired electrons to nearby nuclei. Although broadband chirp pulses can be applied to improve the DNP performances, the distorted microwave amplitudes in a high-Q resonator introduce artefacts on the DNP field profile. We show that the application of chirp pulses with a bandwidth tuned to the EPR linewidth at the SE matching condition yields an improvement in the enhancement by a factor of 2.4 compared to the normal SE condition. Following that, we demonstrate that the NMR sensitivity can be further improved by a combined DNP and electron decoupling technique, which enables direct detection of intramolecular protons on trityl radicals.

Session: HYPERPOLARIZATION 1, time: 5:20 - 5:35 pm

Capturing dynamics in biological systems using DNP-enhanced dipolar recoupling ssNMR spectroscopy

Joanna R. Long1; Nhi Tran1; Fred Mentink-Vigier2; Gwladys Riviere1
1University of Florida, Gainesville, FL; 2National High Magnetic Field Laboratory, Tallahassee, Florida
Membrane proteins, enzymes, and amyloid fibrils provide unique opportunities for gaining mechanistic insights via MAS-DNP ssNMR spectroscopy in regimes that are challenging or unattainable to traditional ssNMR approaches. They also provide unique challenges for optimal radical incorporation, preserving native environments and structural conformers, and sustaining nuclear spin coherences under DNP conditions. I will present strategies to ensure reproducible polarization enhancements and to maintain sample integrity together with ssNMR measurements demonstrating the utility of DNP for making high resolution structural measurements and providing mechanistic insights. Examples will include measurements of structural plasticity in a membrane-active, amphipathic peptide important to pulmonary surfactant; enzyme mechanistic insights for microcrystalline Tryptophan Synthase; and examination of quaternary protein assemblies important to functional amyloids in bacterial biofilms.