The cytochrome P450scc system opens an alternate pathway of vitamin D3 metabolism
The cytochrome P450scc system opens an alternate pathway of vitamin D3 metabolism
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DOI：
10.1111/j.1742-4658.2005.04819.x
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发表时间：
2005-08-01
期刊：
影响因子：
5.4
通讯作者：
Tuckey, RC
中科院分区：
文献类型：
--
作者：
Slominski, A;Semak, I;Tuckey, RC
我们证明，重建系统或分离的肾上腺线粒体中的细胞色素 P450scc (CYP11A1) 可以代谢维生素 D3。与重构酶反应的主要产物是20-羟基胆钙化醇和20,22-二羟基胆钙化醇，产率分别为原始维生素D3底物的16%和4%。三羟基胆钙化醇是次要产物，可能是由二羟基胆钙化醇的进一步代谢产生的。基于 NMR 分析和 P450scc 的已知特性，我们提出 P450scc 对维生素 D3 的羟基化是连续且立体定向地发生的，最初形成 20(S)-羟基维生素 D3。 P450scc 不代谢 25-羟基维生素 D3，表明 C25 的修饰可保护其免受 P450scc 的作用。肾上腺线粒体还代谢维生素 D3，产生 10 种羟基衍生物，具有维生素 D 三烯发色团的典型紫外光谱。氨基鲁米特抑制表明三种主要代谢物（而非其他）是由 P450scc 作用产生的。因此，肾上腺皮质中存在的非 P450scc 酶似乎在某种程度上有助于维生素 D3 的代谢。我们得出的结论是，重构系统中的纯化 P450scc 或肾上腺线粒体中的 P450scc 可以向维生素 D3 添加一个羟基，随后观察到重构酶发生羟基化，但肾上腺线粒体则不然。其他维生素 D3 代谢物是由肾上腺线粒体中其他酶的作用产生的。这些发现似乎定义了涉及维生素 D3 的新代谢途径，但这些途径仍有待表征。
We show that cytochrome P450scc (CYP11A1) in either a reconstituted system or in isolated adrenal mitochondria can metabolize vitamin D3. The major products of the reaction with reconstituted enzyme were 20-hydroxycholecalciferol and 20,22-dihydroxycholecalciferol, with yields of 16 and 4%, respectively, of the original vitamin D3 substrate. Trihydroxycholecalciferol was a minor product, likely arising from further metabolism of dihydroxycholecalciferol. Based on NMR analysis and known properties of P450scc we propose that hydroxylation of vitamin D3 by P450scc occurs sequentially and stereospecifically with initial formation of 20(S)-hydroxyvitamin D3. P450scc did not metabolize 25-hydroxyvitamin D3, indicating that modification of C25 protected it against P450scc action. Adrenal mitochondria also metabolized vitamin D3 yielding 10 hydroxyderivatives, with UV spectra typical of vitamin D triene chromophores. Aminogluthimide inhibition showed that the three major metabolites, but not the others, resulted from P450scc action. It therefore appears that non-P450scc enzymes present in the adrenal cortex to some extent contribute to metabolism of vitamin D3. We conclude that purified P450scc in a reconstituted system or P450scc in adrenal mitochondria can add one hydroxyl group to vitamin D3 with subsequent hydroxylation being observed for reconstituted enzyme but not for adrenal mitochondria. Additional vitamin D3 metabolites arise from the action of other enzymes in adrenal mitochondria. These findings appear to define novel metabolic pathways involving vitamin D3 that remain to be characterized.