Cytochrome P450 2D6: Structure, Function, Regulation and Polymorphism - Paperbackby Shufeng Zhou (Author) Cytochromes are proteins that catalyze electron transfer reactions of well known metabolic pathways and are classified in various superfamilies. The CYP, or P450, superfamily accounts for 90% of the oxidative metabolism of clinical drugs. One member of this superfamily, P450 2D6 (or CYP2D6), singlehandedly metabolizes about 25% of all medications in the human liver. Cytochrome P450 2D6: Structure, Function, Regulation, and