Cytochrome P450 (cyp)

The cytochromes P450 (P450s or CYPs) form a superfamily of enzymes found in organisms from archaea and bacteria through to man (Munro et al. 2007). P450s were discovered as a consequence of their unusual UV-visible absorbance properties, originating from their heme cofactor, which is bound to the protein through a cysteine sulfur in its thiolate form (Denisov et al. 2005). This heme iron coordination state gives rise to an absorption band at ~450 nm when the P450 heme iron is in the reduced (ferrous) state and bound to the inhibitor carbon monoxide (CO). This absorbance spectrum explains the title P450 (or pigment at 450 nm). Early studies were done independently by Martin Klingenberg and by David Garfinkel (Klingenberg 1958; Garfinkel 1958). This P450 spectrum was first reported by Klingenberg, who prepared rat liver microsomes and then reduced the sample with NADPH (or dithionite) and...