Guryev O, Carvalho R A, Usanov S, Gilep A, Estabrook R W
Department of Biochemistry, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390-9038, USA.
Proc Natl Acad Sci U S A. 2003 Dec 9;100(25):14754-9. doi: 10.1073/pnas.2336107100. Epub 2003 Dec 1.
Metabolites of vitamin D3 (D3) (cholecalciferol) are recognized as enzymatically formed chemicals in humans that can influence a wide variety of reactions that regulate a large number of cellular functions. The metabolism of D3 has been extensively studied, and a role for three different mitochondrial cytochrome P450s (CYP24A, CYP27A, and CYP27B1) has been described that catalyze the formation of the 24(OH), 25(OH), and 1(OH) metabolites of D3, respectively. The hormone 1,25-dihydroxyvitamin D3 has been most extensively studied and is widely recognized as a regulator of calcium and phosphorous metabolism. Hydroxylated metabolites of D3 interact with the nuclear receptor and thereby influence growth, cellular differentiation, and proliferation. In this article, we describe in vitro experiments using purified mitochondrial cytochrome P450scc (CYP11A1) reconstituted with the iron-sulfer protein, adrenodoxin, and the flavoprotein, adrenodoxin reductase, and show the NADPH and time-dependent formation of two major metabolites of D3 (i.e., 20-hydroxyvitamin D3 and 20,22-dihydroxyvitamin D3) plus two unknown minor metabolites. In addition, we describe the metabolism of 7-dehydrocholesterol by CYP11A1 to a single product identified as 7-dehydropregnenolone. Although the physiological importance of these hydroxylated metabolites of D3 and their in vivo formation and mode of action remain to be determined, the rate with which they are formed by CYP11A1 in vitro suggests an important role.
维生素D3（D3）（胆钙化醇）的代谢产物被认为是人体内通过酶促形成的化学物质，可影响多种调节大量细胞功能的反应。D3的代谢已得到广泛研究，已描述了三种不同的线粒体细胞色素P450（CYP24A、CYP27A和CYP27B1）的作用，它们分别催化D3的24（OH）、25（OH）和1（OH）代谢产物的形成。激素1,25-二羟基维生素D3的研究最为广泛，被广泛认为是钙和磷代谢的调节剂。D3的羟基化代谢产物与核受体相互作用，从而影响生长、细胞分化和增殖。在本文中，我们描述了使用纯化的线粒体细胞色素P450scc（CYP11A1）与铁硫蛋白、肾上腺皮质铁氧还蛋白和黄素蛋白、肾上腺皮质铁氧还蛋白还原酶重构进行的体外实验，并展示了NADPH和时间依赖性地形成D3的两种主要代谢产物（即20-羟基维生素D3和20,22-二羟基维生素D3）以及两种未知的次要代谢产物。此外，我们描述了CYP11A1将7-脱氢胆固醇代谢为一种单一产物，鉴定为7-脱氢孕烯醇酮。尽管D3的这些羟基化代谢产物的生理重要性及其体内形成和作用方式仍有待确定，但它们在体外由CYP11A1形成的速率表明其具有重要作用。
