Figure 3.

Catalytic mechanism of P450 enzymes. P450s are usually mono-oxygenases, catalyzing the insertion of one of the atoms of molecular oxygen into a substrate, the second atom of oxygen being reduced to water. The most frequently catalyzed reaction is hydroxylation (O insertion) using the very reactive and electrophilic iron-oxo intermediate (species [C], bottom row). The hydroperoxo form of the enzyme (species [B]-) is also an electrophilic oxidant catalyzing OH+ insertion. Nucleophilic attack can be catalyzed by species [A]2- and [B]- ; reduction, isomerization or dehydration are catalyzed by the oxygen-free forms of the enzyme. This, together with the variety of the apoproteins and intrinsic reactivity of all their substrates explains the extraordinary diversity of reactions catalyzed by P450 enzymes.

Werck-Reichhart and Feyereisen Genome Biology 2000 1:reviews3003.1-reviews3003.9   doi:10.1186/gb-2000-1-6-reviews3003