An ODNP Probe to Study Hydration Dynamics in Membrane Protein

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Project Summary / Abstract The proposed research focuses on the development of turn-key instrumentation for liquid-state Overhauser Dynamic Nuclear Polarization (ODNP) spectroscopy to study the site-specific translational dynamics of water molecules located at the interface of bio-macromolecules such as membrane proteins. It will allow researchers to readily perform ODNP experiments in a state-of-the-art commercially available X-band cw/pulsed electron paramagnetic resonance (EPR) spectrometer or, alternatively, in a standalone, benchtop ODNP system. In recent years, DNP has proven to be a robust method to increase signal intensities in NMR experiments in laboratories around the world and substantial progress has been made in adapting DNP for solid- and solution- state NMR spectroscopy. This progress has sparked a new interest in ODNP spectroscopy. Although the method is known since the 1960s it has just recently been applied successfully to study the site-specific translational dynamics of water located at the interface of large bio-macromolecules such as membrane proteins. ODNP can map out the local and site-specific hydration dynamics landscape of membrane proteins and lipid membranes and can provide critical information about the protein structure and dynamics. One of the major challenge of this method is that currently no turn-key, robust instrumentation is available. In this SBIR phase 2 application we will build on the phase 1 success. We propose to develop a continuous- wave ODNP resonator, a microwave power source with integrated NMR spectrometer, and an application package for OpenVnmrJ to completely control the experiment. The resonator will have a large conversion factor to reduce the required microwave power and therefore sample heating. The successful development of this technology will provide researchers access to instrumentation allowing them to incorporate ODNP spectroscopy in their research routine without the hassle of troubleshooting home-built equipment. This will greatly proliferate the method and is of large interest to many projects funded by the U.S. National Institutes of Health.