Date of Graduation

8-2016

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Chemistry (PhD)

Degree Level

Graduate

Department

Chemistry & Biochemistry

Advisor/Mentor

Millett, Francis S.

Committee Member

Durham, Bill

Second Committee Member

Davis, Dan J.

Third Committee Member

Thallapuranam, Suresh

Keywords

Pure sciences; Cytochrome; Electron transfer; Kinetics; Mitochondria; Redox potential

Abstract

Electron transfer between mitochondrial proteins complexes represents the primary means by which living things acquire the requisite energy for survival. The coupling of electron transfer to proton translocation creates an electrochemical gradient that drives the synthesis of highly energetic compounds such as ATP. The purpose of these studies is to measure rates of electron transfer and elucidate the important governing factors in the redox events involving cytochrome bc1, cytochrome c and cytochrome oxidase. Using rapid initiation of redox events triggered by laser flash excitation of ruthenium compounds, and strategically monitoring unique spectral properties of these proteins in the visible region of the electromagnetic spectrum, rates of electron transfer can be determined for native and mutant forms of the proteins. Per Rudolph Marcus' Nobel-winning theory, reorganization energy and redox potential difference between two centers dictate, to a great degree, the rate of electron transfer -- provided that conformational gating is not rate-limiting. Specifically, the internal kinetics of rapid electron transfer in cytochrome bc1 from species Rhodobacter capsulatus is reported in novel fashion. The effects of substrate and inhibitors on the enzyme are discussed. Rate information for mutant constructs of R. cap bc1 is provided to contribute important structure/function information about the protein and its subunits. Additionally, the effect of altering the redox potential of cytochrome c on kinetic rates of rapid electron transfer to the CuA center of cytochrome oxidase is examined, showing for the first time that the electron transfer from cytochrome c to CuA obeys Marcus' predictions.

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