VIBRATIONAL SPECTROSCOPY OF REDOX METALLOPROTEINS

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This proposal seeks to apply modern vibrational spectroscopic probes (Principally resonance Raman (RR), infrared (IR), time- resolved laser spectroscopies, and related techniques) to selected problems in the chemistry and biophysics of redox metalloproteins. The objective is to understand the fundamental factors which influence the function of the active sites of these essential biomolecules. We are concerned with how these proteins effect their critical metabolic functions of facile electron transfer and small molecule (e.g., 02) activation, corollary phenomena such as molecular switching and thermodynamic tuning of electron transfer, and coupled functions such as redox-linked proton pumping. We will concentrate on the "blue" copper proteins and cytochrome c oxidase (CcO). These systems are chosen because of their intrinsic interest and the generality of the issues involved. Specific projects to be undertaken include the following. 1. RR studies aimed at establishing specific relationships between the vibrational observables and the structure function and dynamics of the blue copper active site. 2. Fundamental RR and IR characterization of CcO, including detailed RR excitation profiles and isotope studies. 3. Time-resolved vibrational studies of CcO dynamics, with the objective of characterizing the ligation and electron transfer transients in the functional reactivity of the enzyme. 4. RR studies aimed at elucidating the proton translocation function of CcO. 5. Vibrational characterization of Rieske-type iron-sulfur- nitrogen proteins. 6. Vibration 1 characterization of the newly discovered cytochrome beta alpha 3 from Thermus thermophilus. 7. Characterization of synthetic complexes which may mimic the coupled Fe-Cu cytochrome alpha 3-CuB site of CcO 8. Study of the effects of extreme pressure upon the spectroscopy and long-range electron transfer dynamics of externally metal- labelled and metal-substituted proteins.