人胎盘匀浆中加单氧酶活性的研究：对多种底物和抑制剂的体外反应

A study of monooxygenase activity in human placental homogenates: in vitro behaviour towards a number of substrates and inhibitors.

作者信息

Kaelin A C, Cummings A J

出版信息

Biochem Pharmacol. 1983 Aug 15;32(16):2421-6. doi: 10.1016/0006-2952(83)90686-x.

Abstract

The in vitro effects of cimetidine, metyrapone, SKF-525A and alpha-naphthoflavone on the monooxygenase activity in human placental tissue have been determined by indirect fluorimetric assay methods in placental homogenates from five maternal smokers. The inhibitor concentrations producing half-maximum inhibition (I50 values) were calculated for the O-deethylation of 7-ethoxycoumarin and 7-ethoxyphenoxazone, and the hydroxylation of 2,5-diphenyloxazole. The results indicate that cimetidine is a weak inhibitor of the placental monooxygenase system, resembling metyrapone and SKF-525A in its effects rather than alpha-naphthoflavone. Characterization of the behaviour of the three substrates towards placental monooxygenase activity indicates a much greater enzymic affinity for 7-ethoxyphenoxazone than for 7-ethoxycoumarin or 2,5-diphenyloxazole.

摘要

已通过间接荧光测定法，对来自五名吸烟孕妇胎盘匀浆中的西咪替丁、甲吡酮、SKF - 525A和α - 萘黄酮对人胎盘组织中单加氧酶活性的体外作用进行了测定。计算了对7 - 乙氧基香豆素和7 - 乙氧基吩恶嗪的O - 脱乙基反应以及2,5 - 二苯基恶唑的羟基化反应产生半数最大抑制作用的抑制剂浓度（I50值）。结果表明，西咪替丁是胎盘单加氧酶系统的弱抑制剂，其作用类似于甲吡酮和SKF - 525A，而非α - 萘黄酮。三种底物对胎盘单加氧酶活性的行为特征表明，酶对7 - 乙氧基吩恶嗪的亲和力比对7 - 乙氧基香豆素或2,5 - 二苯基恶唑的亲和力大得多。