Model Studies on Biological Energy Conversion Mechanisms

Abstract

<p>This thesis is concerned with the design of ATP-producing physical and chemical model systems and the investigation of the mechanisms of ATP formation at the molecular level. The ultimate purpose of this study is to apply the concepts derived from these model systems to more complex biological systems. The mechanisms of energy transduction in living organisms may then be approached at a molecular level.</p> <p>Based on the study of the model systems, three modes of activation during the ATP-forming chemical steps for either ADP or inorganic phosphate have been identified. They are:</p> <p>(1) Through a one-electron reduction of ADP into a radical form;</p> <p>(2) Through the creation of oxidizing agents with redox potentials sufficient to oxidize inorganic phosphate;</p> <p>(3) Through an activation of phosphate by coordination to a reduced hemecomplex, followed by aerobic oxidation of the resultant phosphate-heme complex.</p> <p>In biological systems, the first mode may involve utilization of a reducing power of an electron transport chain, of a reducing functional group such as thiol in the ATP synthetase. The second mode may involve PS II or generation of delta singlet oxygen by various energy transfer processes. The third mode may involve the coordination of inorganic phosphate to a cytochrome, such as cytochrome-a₃ in an cytochrome-c oxidase complex.</p>