Activation and irreversible binding of regiospecifically labeled catechol estrogen by rat liver microsomes: evidence for differential cytochrome P-450 catalyzed oxidations.
Activation and irreversible binding of regiospecifically labeled catechol estrogen by rat liver microsomes: evidence for differential cytochrome P-450 catalyzed oxidations.
复制标题
大鼠肝微粒体对区域特异性标记的儿茶酚雌激素的激活和不可逆结合：差异细胞色素 P-450 催化氧化的证据。
DOI：
10.1021/bi00416a042
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发表时间：
1988
期刊：
影响因子：
2.9
通讯作者：
Fishman,J
中科院分区：
文献类型：
--
作者：
Jellinck,PH;Fishman,J
修订稿于 1988 年 4 月 6 日收到摘要：在 A 环或 B 环的不同位置用 3H 标记的雌二醇和 2-羟基雌二醇与雄性大鼠肝微粒体一起孵育，随后它们的氧化转化将 3H 转变为 3H20。 14C标记的雌激素或儿茶酚雌激素用于测定与微粒体蛋白共价结合的分数。 2-羟基雌二醇的进一步代谢涉及通过细胞色素 P-450 介导的反应在 C-4 处激活类固醇，并在较小程度上激活 Cl 处的类固醇，如微粒体系统中 NADPH、精胺、SKF-525A 和 CO 的作用所示。谷胱甘肽促进雌二醇或 2-羟基雌二醇 C-4 上 3H 的丢失，但在 Cl 处对此反应影响较小，并在 C-6、7 处抑制该反应。它还消除了 14C 标记的雌二醇和 2-羟基雌二醇与微粒体蛋白的不可逆结合。 NADPH 是谷胱甘肽发挥作用所必需的，既能将 3H 转移为 3H2O，又能通过大鼠肝微粒体从儿茶酚雌激素形成水溶性产物。它不能被 NADP、NAD 或 NADH 替代。抗坏血酸抑制这些酶促反应，但不显着影响雌二醇的初始2-羟基化。还提供了 2-羟基雌二醇在 C-6（或 C-7）处进一步羟基化的证据。这些结果表明细胞色素 P-450 通过电子夺取过程激活儿茶酚雌激素。
Revised Manuscript Received April 6, 1988 abstract: Estradiol and 2-hydroxyestradiol labeled with 3H at different positions in rings A or B were incubated with male rat liver microsomes, and their oxidative transformation was followed by the transfer of 3H into 3H20. 14C-Labeled estrogen or catechol estrogen was used to determine the fraction that becomes bound covalently to microsomal protein. The further metabolism of 2-hydroxyestradiol involves activation of the steroid at C-4 and, to a much lesser extent at Cl, by a cytochrome P-450 mediated reaction as indicated by the effects of NADPH, spermine, SKF-525A, and CO in the microsomal system. Glutathione promoted the loss of 3H from C-4 of either estradiol or 2-hydroxyestradiol but had less effect on this reaction at Cl and inhibited it at C-6, 7. It also abolished the irreversible binding of 14C-labeled estradiol and 2-hydroxyestradiol to microsomal protein. NADPH was needed specifically for glutathione to exert its effect both on the transfer of 3H into 3H20and on the formation of water-soluble products from catechol estrogen by rat liver microsomes. It could not be replaced by NADP, NAD, or NADH. Ascorbic acid inhibited these enzymatic reactions but did not affect significantly the initial 2-hydroxylation of estradiol. Evidence is also provided for the further hydroxylation of 2-hydroxyestradiol at C-6 (or C-7). These results indicate that cytochrome P-450 activates catechol estrogens by an electron abstraction process.