固醇合成抑制剂。5α-胆甾-8(14)-烯-3β-醇-15-酮的油酸酯作为胰腺胆固醇酯酶的底物。

Inhibitors of sterol synthesis. Oleate ester of 5 alpha-cholest-8(14)-en-3 beta-ol-15-one as a substrate for pancreatic cholesterol esterase.

作者信息

Stephens T W, Schroepfer G J

机构信息

Department of Biochemistry, Rice University, Houston, TX.

出版信息

Biochim Biophys Acta. 1988 Dec 16;963(3):395-400. doi: 10.1016/0005-2760(88)90307-4.

DOI:10.1016/0005-2760(88)90307-4

PMID:3196743

Abstract

5 alpha-Cholest-8(14)-en-3 beta-yl-15-one oleate (15-ketosteryl oleate), the oleate ester of a compound with the capacity to lower serum cholesterol, was effectively hydrolyzed by partially purified porcine pancreatic cholesterol esterase with an apparent Km of 0.28 +/- 0.01 mM and a Vmax of 0.62 +/- 0.01 mumol/min per mg protein compared to an apparent Km of 0.19 +/- 0.02 mM and a Vmax of 0.37 +/- 0.02 mumol/min per mg protein for cholesteryl oleate. The 15-ketosteryl oleate was also hydrolyzed by highly purified rat pancreatic cholesterol esterase with an apparent Km of 0.20 +/- 0.01 mM and a Vmax of 86.7 +/- 3.0 mumol/min per mg protein compared to an apparent Km of 0.43 +/- 0.01 mM and a Vmax of 119.8 +/- 2.6 mumol/min per mg protein for cholesteryl oleate. 15-Ketosteryl oleate is, therefore, a good substrate for pancreatic cholesterol esterase from either source. The 15-ketosterol is a weak competitive inhibitor of partially purified porcine pancreatic cholesterol esterase when cholesteryl oleate is the substrate.

摘要

5α-胆甾-8(14)-烯-3β-基-15-酮油酸酯（15-酮甾醇油酸酯），一种具有降低血清胆固醇能力的化合物的油酸酯，被部分纯化的猪胰胆固醇酯酶有效水解，其表观 Km 为 0.28±0.01 mM，Vmax 为 0.62±0.01 μmol/分钟每毫克蛋白质，相比之下，油酸胆固醇酯的表观 Km 为 0.19±0.02 mM，Vmax 为 0.37±0.02 μmol/分钟每毫克蛋白质。15-酮甾醇油酸酯也被高度纯化的大鼠胰胆固醇酯酶水解，其表观 Km 为 0.20±0.01 mM，Vmax 为 86.7±3.0 μmol/分钟每毫克蛋白质，相比之下，油酸胆固醇酯的表观 Km 为 0.43±0.01 mM，Vmax 为 119.8±2.6 μmol/分钟每毫克蛋白质。因此，15-酮甾醇油酸酯是来自任何一种来源的胰胆固醇酯酶的良好底物。当以油酸胆固醇酯为底物时，15-酮甾醇是部分纯化的猪胰胆固醇酯酶的弱竞争性抑制剂。