The proposed research focuses on the development of a turn-key resonator 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. 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 challenges in ODNP spectroscopy is microwave induced sample heating. In this SBIR Phase I application we propose to develop a turn-key, ODNP resonator compatible with state-of-the-art continuous wave or pulsed X-Band EPR spectrometer, which can be found in many academic spectroscopy facilities. The resonator will have a much higher microwave conversion factor compared to conventional rectangular or circular EPR cavities. In addition, the low Q resonance structure will allow pulsed ODNP experiments to further minimize microwave induced heating by reducing the average power required to saturate the EPR transitions. 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.
Project Summary / Abstract Overhauser Dynamic Nuclear Polarization (ODNP) spectroscopy can be used to study the hydration dynamics of bio-macromolecules such as membrane proteins, but currently there is no cost-effective, turn-key ODNP resonator available. This severely limits the usage of the technique. The proposed ODNP resonator is an add- on to state-of-the-art cw/pulsed EPR spectrometer that can be found in many academic spectroscopy facilities. This will make the method available to a much broader audience and proliferate research that is at the heart of the National Institutes of Health.
