Hemoproteins and related models in hydroxylation reactions of organic compounds Part I. Structure, function and catalytic activity of cytochrome P-450 and related models

Cytochromes P-450 are widely spread in mammals, plants and microorganisms. These enzyme systems are able to catalyze chemical reactions of various organic compounds with molecular oxygen in a so-called mixed function oxidation reaction. All P-450 enzymes consist of an electron transfer component and a terminal oxidase with iron protoporphyrin IX as the prosthetic group. These enzyme systems also catalyze substrate conversion reactions of organic compounds by means of various hydroperoxides and H₂O₂, respectively. In spite of some similarities, the mechanisms of the H₂O₂-dependent reactions catalyzed by horse-radish peroxidase and P-450 differ significantly. On comparing the peroxide-dependent catalysis of P-450 and iron porphyrin complexes, however, a number of common characteristics have been analyzed.