Laethem R M, Koop D R
Department of Pharmacology, Oregon Health Sciences University, Portland 97201.
Mol Pharmacol. 1992 Dec;42(6):958-63.
Microsomes prepared from COS-1 cells transiently expressing rabbit cytochromes P450 2C1 and 2C2 catalyzed the metabolism of arachidonic acid to predominantly 11,12- and 14,15-epoxyeicosatrienoic acids (EETs) when microsomal epoxide hydrolase activity was inhibited by 0.2 mM 1,2-epoxy-3,3,3-trichloropropane. P450 2C2 catalyzed the formation of 11,12-EET and 14,15-EET at a ratio of 3.0 and also produced 19-hydroxyeicosatetraenoic acid (19-HETE). The 11,12-EET, 14,15-EET, and 19-HETE represented 48.3, 15.9, and 12.8%, respectively, of the total metabolites formed. P450 2C1 produced a similar but distinct ratio of 11,12-EET to 14,15-EET (2.0) and did not produce any detectable 19-HETE. The 11,12-EET and 14,15-EET represented 63.0 and 31.1%, respectively, of the total metabolites formed. The 8,9- and 5,6-EETs were not detected with either enzyme. The ratio of the 11,12-EET to 14,15-EET was 1.5 with P450 2CAA, a P450 arachidonic acid epoxygenase (P450 2CAA) that had an amino-terminal sequence identical to that of P450 2C2 [J. Biol. Chem. 267:5552-5559 (1992)]. P450 2C1, 2C2, and 2CAA metabolized lauric acid. The ratio of omega-1- to omega-hydroxylated laurate was 3.6, 3.4, and 2.4 for P450 2CAA, P450 2C2, and P450 2C1, respectively. Purified P450 2CAA had a slightly greater apparent molecular weight than expressed P450 2C2 on sodium dodecyl sulfate-polyacrylamide gels. The results clearly establish that rabbit P450 2C1 and 2C2 are arachidonic acid epoxygenases, and they suggest that P450 2CAA and 2C2 are very similar but may not be identical isoforms.
当微粒体环氧化物水解酶活性被0.2 mM 1,2-环氧-3,3,3-三氯丙烷抑制时，从瞬时表达兔细胞色素P450 2C1和2C2的COS-1细胞制备的微粒体催化花生四烯酸代谢，主要生成11,12-和14,15-环氧二十碳三烯酸（EETs）。P450 2C2催化生成11,12-EET和14,15-EET的比例为3.0，还生成19-羟基二十碳四烯酸（19-HETE）。11,12-EET、14,15-EET和19-HETE分别占总代谢产物的48.3%、15.9%和12.8%。P450 2C1生成的11,12-EET与14,15-EET比例相似但不同（2.0），且未检测到任何可检测的19-HETE。11,12-EET和14,15-EET分别占总代谢产物的63.0%和31.1%。两种酶均未检测到8,9-和5,6-EETs。P450 2CAA（一种花生四烯酸环氧化酶，其氨基末端序列与P450 2C2相同[《生物化学杂志》267:5552 - 5559(1992)]）生成的11,12-EET与14,15-EET比例为1.5。P450 2C1、2C2和2CAA均代谢月桂酸。P450 2CAA、P450 2C2和P450 2C1代谢月桂酸生成ω-1-羟基月桂酸与ω-羟基月桂酸的比例分别为3.6、3.4和2.4。在十二烷基硫酸钠-聚丙烯酰胺凝胶上，纯化的P450 2CAA的表观分子量比表达的P450 2C2略大。结果清楚地表明兔P450 2C1和2C2是花生四烯酸环氧化酶，并且表明P450 2CAA和2C2非常相似但可能不是相同的同工型。
