Wood A W, Ryan D E, Thomas P E, Levin W
J Biol Chem. 1983 Jul 25;258(14):8839-47.
High pressure liquid chromatographic systems capable of resolving at least 28 known and potential metabolites of 17 beta-hydroxy-4-androsten-3-one (testosterone) and 4-androstene-3,17-dione (androstenedione) were used to quantitatively assess the metabolism of the two steroids in monooxygenase systems reconstituted with five purified rat liver cytochrome P-450 isozymes. Cytochromes P-450a, -b, -c, -d, and -e catalyzed the oxidation of testosterone at overall rates of 21, 27, 2, 0.7, and 3 nmol/min/nmol of cytochrome P-450, respectively; while the corresponding rates for total androstenedione metabolism were 12, 62, 1.5, 0.3, and 5. Cytochrome P-450a catalyzed the oxidation of testosterone and androstenedione almost exclusively to their respective 7 alpha-hydroxy metabolites. Cytochrome P-450b catalyzed the oxidation of testosterone to androstenedione and 16 alpha- and 16 beta-hydroxytestosterone in approximately equal molar ratios. However, this same hemoprotein exhibited a marked stereoselectivity in the metabolism of androstenedione since the molar ratio of 16 alpha- and 16 beta-hydroxyandrostenedione was greater than 1:10. Cytochrome P-450e catalyzed the oxidation of both steroids to the same products as cytochrome P-450b, but at approximately 10% of the rate. Cytochromes P-450c and P-450d catalyzed the oxidation of testosterone and androstenedione regio- and stereospecifically to their respective 6 beta-hydroxy metabolites. These results indicate that certain cytochrome P-450 isozymes show marked positional specificity in the metabolism of both testosterone and androstenedione, and that the rate as well as stereoselectivity of the oxidative reactions can be markedly dependent on subtle differences in the structure of the steroid substrate.
能够分离出至少28种已知的和潜在的17β-羟基-4-雄甾烯-3-酮（睾酮）及4-雄烯二酮（雄烯二酮）代谢物的高压液相色谱系统，被用于定量评估这两种类固醇在由五种纯化的大鼠肝脏细胞色素P-450同工酶重构的单加氧酶系统中的代谢情况。细胞色素P-450a、-b、-c、-d和-e催化睾酮氧化的总速率分别为21、27、2、0.7和3 nmol/分钟/每nmol细胞色素P-450；而雄烯二酮总代谢的相应速率分别为12、62、1.5、0.3和5。细胞色素P-450a催化睾酮和雄烯二酮氧化几乎只生成它们各自的7α-羟基代谢物。细胞色素P-450b催化睾酮氧化生成雄烯二酮以及16α-和16β-羟基睾酮，其摩尔比大致相等。然而，这种相同的血红蛋白在雄烯二酮代谢中表现出显著的立体选择性，因为16α-和16β-羟基雄烯二酮的摩尔比大于1:10。细胞色素P-450e催化这两种类固醇氧化生成与细胞色素P-450b相同的产物，但速率约为其10%。细胞色素P-450c和P-450d区域和立体特异性地催化睾酮和雄烯二酮氧化生成它们各自的6β-羟基代谢物。这些结果表明，某些细胞色素P-450同工酶在睾酮和雄烯二酮的代谢中表现出显著的位置特异性，并且氧化反应的速率以及立体选择性可能明显取决于类固醇底物结构的细微差异。
