2/18/2023 0 Comments Nuclear time in resonance![]() Studies of such interactions are crucial to the basic understanding of living systems. This project investigates fundamental aspects of protein dynamics and focuses on the electron-nuclear coupling at the active site of heme proteins. This will be used as an important independent probe of the structure, function, dynamics, and anharmonicity of the heme chromophore that can be applied to other biological systems as well. Femtosecond stimulated Raman scattering instrumentation is also being developed and applied to the study of metal-ligand charge transfer bands. New experiments suggest a dynamic ligand discrimination mechanism in heme protein systems that depend upon the lifetime of the dissociated state relative to its entropy production time. Novel temperature dependent ultrafast kinetic studies reveal the protein-specific entropic and enthalpic contributions to ligand binding transition state barriers. Other techniques, such as nuclear resonance vibrational spectroscopy and magnetic field perturbations are applied to aid in the assignment and characterization of the low frequency (anharmonic) motions. Phase and amplitude excitation profiles of these modes increase understanding of the non-radiative electron-nuclear coupling mechanisms that trigger the coherent oscillations of reaction coordinates. The coherence spectroscopy studies use heme model complexes DFT calculations, x-ray structures, and normal coordinate structural decomposition to quantify the protein-induced symmetry lowering distortions of the heme that activate these (anharmonic) low frequency modes. Low-frequency heme distortions (e.g., ruffling and doming) are involved in the reorganization of energy associated with such fundamental reactions such as electron transport and ligand binding. Coherence techniques are a unique probe of the vibrational spectrum in the region below room temperature (kBT ~ 200cm-1), which contains the thermally accessible modes most likely to be utilized as reaction coordinates. Temperature dependent ultrafast kinetics, resonance Raman scattering, and femtosecond coherence spectroscopy, are used in this project to probe the structure/function/dynamics relationships of biomolecules such as heme proteins. Understanding the role of vibrational energy in activating biomolecules to perform their various functions is a major goal that will extend existing knowledge of biomolecular reaction dynamics. Molecular Biophysics, FRONTIERS IN BIO RES (FIBR), PHYSICS OF LIVING SYSTEMS, International Research CollabÄ 40100 NSF RESEARCH & RELATED ACTIVIT 040100 NSF RESEARCH & RELATED ACTIVIT 040100 NSF RESEARCH & RELATED ACTIVIT 040100 NSF RESEARCH & RELATED ACTIVITÄ¡144, 1164, 5946, 5979, 7298, 7465, 9178, 9183, 9251, BIOT, SMET Primary Place of Performance Congressional District: Paul Champion (Principal Investigator) J Timothy Sage (Co-Principal Investigator).MCB Div Of Molecular and Cellular Bioscience ![]() Resonance Raman Studies of Electron-Nuclear Coupling, Time Resolved Dynamics, and Magnetic Perturbations of Biomolecules NSF Org:
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