University of Virginia Health System

Nuclear Magnetic Resonance in Chemistry Research in the Bryant laboratory employs magnetic resonance methods to study a wide range of molecular dynamics. A primary focus derives from unique instrumentation that permits study of the magnetic field dependence of nuclear spin-lattice relaxation rates. This experimental approach provides an accurate means for characterizing specific intra- and inter-molecular motions over the time range from 1 ms to 0.5 ps. Major efforts include characterizing internal hinge motions in proteins, measuring localized diffusion constants for critical solutes diffusing in the vicinity of unique sites in membranes, and measuring the frequencies of critical side chain motions in protein active sites. In related work we exploit the effects of a freely diffusing paramagnetic small molecule to characterize the details of how one molecule contacts and explores another. In the protein case, the structural resolution is provided by the 2-dimensional NMR spectral assignments and we may investigate the nature of the intermolecular contacts with the protein as a function of size and charge which permits study of the fundamental aspects of the protein surface energetics that are crucial for molecular recognition processes. An applied and very practical aspect of these experiments is the design and delivery of magnetic contrast agents for applications in clinical magnetic resonance imaging protocols as well as the characterization of liquids in microporous materials. We also utilize the pressure dependence of amide hydrogen exchange reactions with deuterium oxide to characterize rare structural fluctuations in proteins in a structurally resolved way. Again, we exploit multidimensional NMR spectroscopy to provide the kinetic information at each amide proton position in the folded protein structure. We are primarily exploring how the exchange events are a function of the protein stability and how these pressure measurements provide insights to the structural fluctuations that provide proteins with their catalytic effectiveness.

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