A Model of Specificity and Selectivity of Mammalian Cytochrome P450 Monooxy-genases

Multiple molecular dynamics simulations and a systematic analysis of sequence and structure of mammalian cytochrome P450 monooxygenases were performed to investigate the structural basis of their specificity and selectivity. While the substrate binding cavity is mobile, the protein core and the access funnel to the heme are rigid. High mobility of the substrate binding pocket is consistent with the broad substrate profile observed for these enzymes, while the rigid core mediates regioselectivity by controlling substrate access to the heme. For enzymes with narrow heme access funnels, only highly accessible positions in substrates are accepted, while for enzymes with a more exposed heme regioselectivity is driven by chemical reactivity of the substrate.