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Cytochrome P450's [1,2,3,E1] are a group of enzymes involved in the oxidative
metabolism of a high number of natural compounds (such as steroids, fatty
acids, prostaglandins, leukotrienes, etc) as well as drugs, carcinogens and
mutagens. Based on sequence similarities, P450's have been classified into
about forty different families [4,5]. P450's are proteins of 400 to 530 amino
acids; the only exception is Bacillus BM-3 (CYP102) which is a protein of 1048
residues that contains a N-terminal P450 domain followed by a reductase
domain. P450's are heme proteins. A conserved cysteine residue in the C-terminal part of P450's is involved in binding the heme iron in the fifth
coordination site. From a region around this residue, we developed a ten
residue signature specific to P450's.
The term 'cytochrome' P450, while commonly used, is incorrect as P450
are not electron-transfer proteins; the appropriate name is P450 'heme-
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