A critical role of protein‐bound water in the catalytic cycle of cytochrome P‐450 camphor

Abstract The rates of NADH oxidation during the hydroxylation of camphor by cytochrome P-450 cam were followed in the presence of co-solvents used to increase the osmotic pressure surrounding the protein-bound water. As a result, the measured V max decreases independently of the perturbant tested. Roughly 28 molecules of water, involved during the catalytic cycle, are deduced from the variation of V max as a function of osmotic pressure. These molecules, in part, could be those present in the cytochrome P.450 cam -putidaredoxin interface.