Fig. 6. Homology model for etomidate binding to CYP11B1. The binding pocket of CYP11B1 is depicted based on high-resolution crystal structures of related cytochromes.147Etomidate is bound within the binding pocket, oriented to form a strong coordinate bond between its free imidazole nitrogen and the heme iron of the enzyme. (This figure was kindly provided by Keith W. Miller, D. Phil., and Shunmugasundararaj Sivananthaperumal, Department of Anesthesia, Critical Care, and Pain Medicine, Massachusetts General Hospital, Boston, Massachusetts.)