Aoyama Y, Yoshida Y, Sonoda Y, Sato Y
J Biol Chem. 1987 Jan 25;262(3):1239-43.
Metabolism of 32-hydroxy-24,25-dihydrolanosterol (lanost-8-ene-3 beta,32-diol), a posturated intermediate of the 14 alpha-demethylation (removal of C-32) of 24,25-dihydrolanosterol (lanost-8-en-3 beta-ol), by a reconstituted system consisting of yeast cytochrome P-450 which catalyzes lanosterol 14 alpha-demethylation (cytochrome P-45014DM) (Yoshida, Y., and Aoyama, Y. (1984) J. Biol. Chem. 259, 1655-1660 and Aoyama, Y., Yoshida, Y., and Sato, R. (1984) J. Biol. Chem. 259, 1661-1666) and NADPH-cytochrome P-450 reductase was studied. The reconstituted system converted both 32-hydroxy-24,25-dihydrolanosterol and 24,25-dihydrolanosterol to 4,4-dimethyl-5 alpha-cholesta-8,14-dien-3 beta-ol, the 14 alpha-demethylated product of the latter. The metabolism of these compounds was inhibited by a low concentration of ketoconazole which is a potent cytochrome P-45014DM inhibitor. Affinity of cytochrome P-45014DM for 32-hydroxy-24,25-dihydrolanosterol was about 20 times higher than for 24,25-dihydrolanosterol and the cytochrome metabolized the former about 4 times faster than the latter under the experimental conditions. Spectral analysis suggested that the 32-hydroxyl group of 32-hydroxy-24,25-dihydrolanosterol interacted with the heme iron of the oxidized cytochrome and this interaction might support the high affinity of this compound for the cytochrome. These lines of evidence indicate that 32-hydroxy-24,25-dihydrolanosterol is the intermediate of the 14 alpha-demethylation of 24,25-dihydrolanosterol by cytochrome P-45014DM. It is also clear that the cytochrome catalyzes further metabolism of the 32-hydroxylated intermediate to the 14 alpha-demethylated product with higher efficiency than the 32-hydroxylation of the substrate. Cytochrome P-45014DM is thus classified as lanosterol C14-C32 lyase.
对32-羟基-24,25-二氢羊毛甾醇（羊毛甾-8-烯-3β,32-二醇）的代谢进行了研究，它是24,25-二氢羊毛甾醇（羊毛甾-8-烯-3β-醇）14α-去甲基化（去除C-32）的假定中间体，代谢由一个重组系统完成，该系统包含催化羊毛甾醇14α-去甲基化的酵母细胞色素P-450（细胞色素P-45014DM）（吉田洋和青山洋（1984年）《生物化学杂志》259卷，第1655 - 1660页；青山洋、吉田洋和佐藤润（1984年）《生物化学杂志》259卷，第1661 - 1666页）以及NADPH-细胞色素P-450还原酶。该重组系统将32-羟基-24,25-二氢羊毛甾醇和24,25-二氢羊毛甾醇都转化为4,4-二甲基-5α-胆甾-8,14-二烯-3β-醇，即后者的14α-去甲基化产物。这些化合物的代谢受到低浓度酮康唑的抑制，酮康唑是一种有效的细胞色素P-45014DM抑制剂。细胞色素P-45014DM对32-羟基-24,25-二氢羊毛甾醇的亲和力比对24,25-二氢羊毛甾醇高约20倍，并且在实验条件下，该细胞色素代谢前者的速度比后者快约4倍。光谱分析表明，32-羟基-24,25-二氢羊毛甾醇的32-羟基与氧化型细胞色素的血红素铁相互作用，这种相互作用可能支持了该化合物对细胞色素的高亲和力。这些证据表明，32-羟基-24,25-二氢羊毛甾醇是细胞色素P-45014DM催化24,25-二氢羊毛甾醇14α-去甲基化的中间体。同样清楚的是，该细胞色素催化32-羟基化中间体进一步代谢为14α-去甲基化产物的效率高于底物的32-羟基化。因此，细胞色素P-45014DM被归类为羊毛甾醇C14-C32裂解酶。
