REDUCED OXY INTERMEDIATE OBSERVED IN D251N CYTOCHROME P450(CAM)

Cytochrome P450s are ubiquitous heme proteins responsible for various oxidative metabolic processes. The overall rate-determining step in th e catalytic cycle of native cytochrome P450(cam) is the reduction of t he dioxygen complex, which has made detection of catalytic intermediat es after this reduction impossible. However, for the site-specific mut ant D251N cytochrome P450(cam) (which affects proton transfer near the catalytic center), the overall rate-determining step occurs after the reduction of oxy-P450. As a consequence, we have observed in the UV-v isible spectrum during catalytic turnover a new intermediate that is o ne electron reduced from oxy-P450 with an intact dioxygen bond.