Stoichiometry of Multi-Protein Complexes Determine Catalytic Activity for Redox Proteins

摘要

Cytochrome P450 (P450) reductase (CPR) serves as a redox protein partner for a number of different proteins critical in biological transformation reactions such as heme oxygenase in heme degradation, P450 species in drug metabolism, and cytochrome b_5 in fatty acid desaturation and elongation. Protein complexation facilitates the passage of electrons via CPR to the protein partners for catalysis to occur. The mechanism by which CPR structure enables this catalytic promiscuity is unclear, but undoubtedly relevant to the activities of the resultant complex(es) in the cell. A single binary functional complex between CPR and protein partners, such as cytochrome c (CC) or P450s, is generally accepted in the literature. However, in our studies this simple model failed to explain experimental observations for complexes between CPR and CC or P450.