Relaxation kinetics of cytochrome P450 reductase: internal electron transfer is limited by conformational change and regulated by coenzyme binding

Results demonstrate that replacement of Trp-676 with His-676 in the cytochrome P450 reductase results in about 2-fold reduction in the rate of electron transfer in both 'forward' and 'reverse' directions. Also, the internal electron transfer in two- and three-electron reduced cytochrome P450 reductase is slow.