title: Insights into the structure, function, and regulation of human cytochrome P450 1A2.
abstract: CYP1A2 is one of the major CYPs in human liver ( approximately 13%) and metabolises a variety of clinically important drugs, such as clozapine, lidocaine, theophylline, tacrine, and leflunomide. CYP1A2 is one of the major enzymes that bioactivate a number of procarcinogens and thus induction of CYP1A2 may increase the carcinogenicity of these compounds. This enzyme also metabolizes several important endogenous compounds including steroids, retinols, melatonin, uroporphyrinogen and arachidonic acid. In the recently published crystal structure of CYP1A2 in complex with alpha-naphthoflavone, its compact active site is closed without clear solvent or substrate access channels. Not surprisingly, CYP1A2 has a relatively small volume of the active site cavity of 375 A(3), which is 44.2% larger than that of CYP2A6 (260 A(3)), but much smaller than that of CYP3A4 (1385 A(3)) and 2C8 (1438 A(3)). Generally, CYP1A2 substrates contain planar ring that can fit the narrow and planar active site of the enzyme. Like many of other CYPs, CYP1A2 is subject to induction and inhibition by a number of compounds. Similar to CYP1A1 and 1B1, CYP1A2 is primarily regulated by the aromatic hydrocarbon receptor (AhR), a ligand-activated transcription factor and a basic helix-loop-helix protein belonging to the Per-Arnt-Sim family of transcription factors. Knockout of Cyp1a2 in mice has provided a very useful tool for the functional investigation of this gene. Further studies are needed to explore the clinical and toxicological significance of CYP1A2.
authors.affiliation: School of Health Sciences, RMIT University, Victoria 3083, Australia. shufeng.zhou@rmit.edu.au
authors.forename: Shu-Feng
authors.initials: SF
authors.lastname: Zhou
authors.forename: Eli
authors.initials: E
authors.lastname: Chan
authors.forename: Zhi-Wei
authors.initials: ZW
authors.lastname: Zhou
authors.forename: Charlie Changli
authors.initials: CC
authors.lastname: Xue
authors.forename: Xinsheng
authors.initials: X
authors.lastname: Lai
authors.forename: Wei
authors.initials: W
authors.lastname: Duan
mesh_terms: D000818:Animals; D019388:Cytochrome P-450 CYP1A2 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D003577:Cytochrome P-450 Enzyme System / Q000737:chemistry / Q000378:metabolism; D004790:Enzyme Induction / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D008099:Liver / Q000201:enzymology*; D051379:Mice; D018345:Mice, Knockout; D004364:Pharmaceutical Preparations / Q000378:metabolism*
chemical_list: D004791:Enzyme Inhibitors; D004364:Pharmaceutical Preparations; D003577:Cytochrome P-450 Enzyme System; D019388:Cytochrome P-450 CYP1A2