Protein-protein interactions, domain motion and electron transfer in the cytochrome P450 mono-oxygenase system. (360G-Wellcome-084116_Z_07_Z)

In the P450 mono-oxygenase system, cytochrome P450 reductase accepts electrons from NADPH, a 2-electron donor, and transfers them one at a time at the appropriate points in the catalytic cycle of cytochrome P450s, which are central to the metabolism of drugs in man. We will use a multidisciplinary approach involving mutagenesis, NMR, SAXS, kinetics and chemical cross-linking to study the structure and function of membrane-bound cytochrome P450 mono-oxygenase complexes, specifically complexes con taining P450 3A4. Studies of appropriately designed mutants of cytochrome P450 reductase will allow us to refine our models for domain movement in the enzyme understand its role in electron transfer to the P450. We shall develop a structural model for the functional reductase cytochrome P450 complex in the membrane and relate the kinetics of formation and dissociation of this complex to substrate turnover by the P450 and the role of cytochrome b5. The results will allow us to develop, for the first time, a structural model of the P450 mono-oxygenase complex in a membrane and to relate this to the physiological electron transfers in this important drug-metabolising system.