The principal objectives of this research are: 1. Elucidate the mechanism in model membranes of electron transfer catalyzed by heme and heme a to gain insight into electron transfer catalyzed by the membrane-bound cytochromes of the inner mitochondrial electron transfer chain. Assess interaction of hemes in non-aqueous phases with oxidants and reductants. Study effect of variation in membrane width, polarity, lipids, etc., and of variation in heme ligands and anions on the rate and mechanism of electron transfer. 2. Utilize covalently-linked multiporphyrin molecules to examine catalysis of trans-membrane electron flow as a model for in vivo trans-membrane multi-heme electron transfer complexes. Assess molecular requirements necessary to encourage trans-membrane catalysis. Elucidate the mechanism of electron transfer catalyzed by these multi-porphyrin centers. 3. Label ubiquinone 10 (and other benzoquinones) with 14C by growing R. rubrum (aerobically) and yeast in the presence of an appropriate precursor. Beef heart mitochondria will also be labelled by exchange in order to assess whether or not the electron transfer membranes of these organisms have tightly-bound ubiquinone. The membranes will be fractionated into complexes I, II, III, and IV, and proteins with covalently-attached benzoquinones (which would be labelled in the R. rubrum and yeast systems). 4. Establish the electrochemical and spectroscopic properties of in vitro immobilized benzoquinones in aprotic, limited protic and aqueous solvents as models for in vivo immobilized benzoquinones. The benzoquinones will be immobilized by attaching them to polypeptide polymers or by studying them in gel phase bilayer vesicles. 5. Study trans-membrane electron transfer catalyzed by a coupled system of ubiquinone and iron porphyrins as a model for the proposed electron transfer between ubiquinone 10 and cytochromes. 6. Assess the possibility of reconstructing complete redox models for cytochrome oxidase, the b-c1 complex and NADH dehydrogenase.
