Metabolic stability of 3-epi-1α,25-dihydroxyvitamin D3 over 1 α 25-dihydroxyvitamin D3: metabolism and molecular docking studies using rat CYP24A1.
Metabolic stability of 3-epi-1α,25-dihydroxyvitamin D3 over 1 α 25-dihydroxyvitamin D3: metabolism and molecular docking studies using rat CYP24A1.
复制标题
3-epi-1α,25-二羟基维生素 D3 超过 1 α 25-二羟基维生素 D3 的代谢稳定性：使用大鼠 CYP24A1 进行代谢和分子对接研究。
DOI：
10.1002/jcb.24576
复制
发表时间：
2013
影响因子：
4
通讯作者：
Reddy,GSatyanarayana
中科院分区：
文献类型：
--
作者：
Rhieu,SteveY;Annalora,AndrewJ;Wang,Guochun;Flarakos,CarolineC;Gathungu,RoseM;Vouros,Paul;Sigüeiro,Rita;Mouriño,Antonio;Schuster,Inge;Palmore,GTayhasR;Reddy,GSatyanarayana
3‐epi‐1α,25‐dihydroxyvitamin D3(3‐epi‐1α,25(OH)2D3), a natural metabolite of 1α,25‐dihydroxyvitamin D3(1α,25(OH)2D3), exhibits potent vitamin D receptor (VDR)‐mediated actions such as inhibition of keratinocyte growth or suppression of parathyroid hormone secretion. These VDR‐mediated actions of 3‐epi‐1α,25(OH)2D3needed an explanation as 3‐epi‐1α,25(OH)2D3, unlike 1α,25(OH)2D3, exhibits low affinity towards VDR. Metabolic stability of 3‐epi‐1α,25(OH)2D3over 1α,25(OH)2D3has been hypothesized as a possible explanation. To provide further support for this hypothesis, we now performed comparative metabolism studies between 3‐epi‐1α,25(OH)2D3and 1α,25(OH)2D3using both the technique of isolated rat kidney perfusion and purified rat CYP24A1 in a cell‐free reconstituted system. For the first time, these studies resulted in the isolation and identification of 3‐epi‐calcitroic acid as the final inactive metabolite of 3‐epi‐1α,25(OH)2D3produced by rat CYP24A1. Furthermore, under identical experimental conditions, it was noted that the amount of 3‐epi‐calcitroic acid produced from 3‐epi‐1α,25(OH)2D3is threefold less than that of calcitroic acid, the analogous final inactive metabolite produced from 1α,25(OH)2D3. This key observation finally led us to conclude that the rate of overall side‐chain oxidation of 3‐epi‐1α,25(OH)2D3by rat CYP24A1 leading to its final inactivation is slower than that of 1α,25(OH)2D3. To elucidate the mechanism responsible for this important finding, we performed a molecular docking analysis using the crystal structure of rat CYP24A1. Docking results suggest that 3‐epi‐1α,25(OH)2D3, unlike 1α,25(OH)2D3, binds to CYP24A1 in an alternate configuration that destabilizes the formation of the enzyme‐substrate complex sufficiently to slow the rate at which 3‐epi‐1α,25(OH)2D3is inactivated by CYP24A1 through its metabolism into 3‐epi‐calcitroic acid. J. Cell. Biochem. 114: 2293–2305, 2013. © 2013 Wiley Periodicals, Inc.
