以对硝基苯酚和对硝基苯葡萄糖醛酸苷为底物，在pH 7.5条件下对大鼠肝微粒体中UDP-葡萄糖醛酸基转移酶和β-葡萄糖醛酸酶活性的干扰。

Interference of UDP-glucuronyltransferase and beta-glucuronidase activity in rat liver microsomes at pH 7.5 with p-nitrophenol and p-nitrophenylglucuronide as substrates.

作者信息

Gigon P L, Bickel M H

出版信息

Enzyme. 1979;24(4):230-8. doi: 10.1159/000458664.

Abstract

Microsomal fraction contains the whole of hepatic UDP-glucuronyltransferase as well as part of beta-glucuronidase. The activities of the two enzymes were assayed under identical conditions using untreated male rat liver microsomes at pH 7.5. In a 30-min incubation with p-nitrophenol and UPD-glucuronic acid, a net glucuronide formation of 0.010 mumol.min-1.g.liver-1 was measured. In the presence of saccharolactone at concentrations selectively blocking beta-glucuronidase, the glucuronidation rate was 0.015 mumol.min-1.g.liver-1. Using the kinetic parameters of beta-glucuronidase (Km = 0.06 mmol/l p-nitrophenylglucuronide, Vm = 0.075 mumol pNP formed.h-1.g.liver-1) determined in the absence of UDP-glucuronic acid, to correct for the beta-glucuronidase's interference on the glucuronidation process, a glucuronide formation of 0.011 mumol.min-1.g.liver-1 was calculated.

摘要

微粒体部分含有全部肝UDP-葡萄糖醛酸基转移酶以及部分β-葡萄糖醛酸酶。在pH 7.5条件下，使用未处理的雄性大鼠肝微粒体，在相同条件下测定这两种酶的活性。在与对硝基苯酚和UPD-葡萄糖醛酸孵育30分钟后，测得葡萄糖醛酸苷的净生成量为0.010微摩尔·分钟⁻¹·克肝脏⁻¹。在存在选择性阻断β-葡萄糖醛酸酶的浓度的糖内酯的情况下，葡萄糖醛酸化速率为0.015微摩尔·分钟⁻¹·克肝脏⁻¹。利用在不存在UDP-葡萄糖醛酸的情况下测定的β-葡萄糖醛酸酶的动力学参数（Km = 0.06毫摩尔/升对硝基苯基葡萄糖醛酸苷，Vm = 0.075微摩尔对硝基苯酚生成·小时⁻¹·克肝脏⁻¹），以校正β-葡萄糖醛酸酶对葡萄糖醛酸化过程的干扰，计算出葡萄糖醛酸苷的生成量为0.011微摩尔·分钟⁻¹·克肝脏⁻¹。