cytochrome p450

A highly diversified set (more than 1500 known sequences) of heme-containing proteins. Frequently called hydroxylases, although P450 proteins can perform a wide spectrum of other reactions. In bacteria they are soluble and approximately 400 amino acids long; eukaryotic P450s are larger - about 500 amino acids. In mammals they are critical for drug metabolism, haemostasis, cholesterol biosynthesis and steroidogenesis; in plants they are involved in plant hormone synthesis, phytoalexin synthesis, flower petal pigment biosynthesis and many unknown functions. In fungi they make ergosterol and they are involved in pathogenesis. Bacterial P450s are key elements in antibiotic synthesis.