Henry H L
Department of Biochemistry, University of California, Riverside 92521.
J Cell Biochem. 1992 May;49(1):4-9. doi: 10.1002/jcb.240490103.
There are three mixed function oxidases which catalyze hydroxylations of vitamin D and its derivatives. These include the hepatic mitochondrial or microsomal vitamin D3-25-hydroxylase and the two renal mitochondrial enzymes which further hydroxylate 25-hydroxyvitamin-D3 (25-OH-D3) to form 24R,25-dihydroxyvitamin D3 (24,25(OH)2D3) and 1,25-dihydroxyvitamin D3 [1,25(OH)2D3], the primary steroid hormonal derivative of vitamin D3. All three enzymes are cytochrome P450 dependent. The two renal mitochondrial enzymes are regulated, usually in a reciprocal fashion. The intracellular signalling systems involved in this regulation include 1,25(OH)2D3 itself and both protein kinases A and C. Recent progress has been made in the purification and cloning of the vitamin D3-25-hydroxylase and the 25-OH-D3-24-hydroxylase. When the 25-OH-D3-1-hydroxylase is purified and cloned, efforts which have thus far been frustrated by its low abundance, fertile new ground for the study of the regulation of vitamin D metabolism at the molecular level will be opened up.
有三种混合功能氧化酶可催化维生素D及其衍生物的羟化反应。这些酶包括肝脏线粒体或微粒体维生素D3-25-羟化酶以及两种肾脏线粒体酶，后者可将25-羟基维生素D3（25-OH-D3）进一步羟化，形成24R,25-二羟基维生素D3（24,25(OH)2D3）和1,25-二羟基维生素D3 [1,25(OH)2D3]，即维生素D3的主要类固醇激素衍生物。这三种酶均依赖细胞色素P450。两种肾脏线粒体酶通常以相互拮抗的方式受到调节。参与这种调节的细胞内信号系统包括1,25(OH)2D3本身以及蛋白激酶A和C。维生素D3-25-羟化酶和25-OH-D3-24-羟化酶的纯化和克隆工作已取得了新进展。当25-OH-D3-1-羟化酶被纯化和克隆时（该酶目前因含量低而阻碍了相关研究），将为在分子水平研究维生素D代谢的调节开辟新的肥沃领域。
