Irshaid Y M, Tephly T R
Mol Pharmacol. 1987 Jan;31(1):27-34.
Two UDP-glucuronosyltransferases (EC 2.4.1.17) were purified from human liver microsomes. Human liver microsomes were solubilized with Emulgen 911 and the UDP-glucuronosyltransferases were separated and purified by chromatofocusing and UDP-hexanolamine Sepharose 4B affinity chromatography. One isoenzyme eluted with an apparent pl of 7.4, displayed a subunit molecular weight of 53,000 after sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), and catalyzed the glucuronidation of p-nitrophenol, 4-methylumbelliferone, alpha-naphthylamine, and estriol, but not that of 4-aminobiphenyl. A second isoenzyme eluted with an apparent pl of 6.2, displayed a subunit molecular weight of 54,000 after SDS-PAGE, and catalyzed the glucuronidation of p-nitrophenol, 4-methylumbelliferone, alpha-naphthylamine, and 4-aminobiphenyl, but not that of estriol. Neither of the purified human liver UDP-glucuronosyltransferases employed estrone, beta-estradiol, testosterone, androsterone, or 5 alpha-androstane-3 alpha,17 beta-diol as substrate. These enzymes displayed apparent Km values in the same order of magnitude for a given substrate. In general, high concentrations of phosphatidylcholine were required for reconstitution of maximal glucuronidation activity. This report documents the existence of multiple UDP-glucuronosyltransferases in human liver.
从人肝微粒体中纯化出两种UDP-葡萄糖醛酸基转移酶（EC 2.4.1.17）。用人乳化剂911溶解人肝微粒体，通过色谱聚焦和UDP-己醇胺琼脂糖4B亲和色谱法分离并纯化UDP-葡萄糖醛酸基转移酶。一种同工酶洗脱时表观pI为7.4，经十二烷基硫酸钠-聚丙烯酰胺凝胶电泳（SDS-PAGE）后显示亚基分子量为53,000，催化对硝基苯酚、4-甲基伞形酮、α-萘胺和雌三醇的葡萄糖醛酸化，但不催化4-氨基联苯的葡萄糖醛酸化。第二种同工酶洗脱时表观pI为6.2，经SDS-PAGE后显示亚基分子量为54,000，催化对硝基苯酚、4-甲基伞形酮、α-萘胺和4-氨基联苯的葡萄糖醛酸化，但不催化雌三醇的葡萄糖醛酸化。纯化的人肝UDP-葡萄糖醛酸基转移酶均未将雌酮、β-雌二醇、睾酮、雄酮或5α-雄甾烷-3α,17β-二醇用作底物。对于给定底物，这些酶的表观Km值在相同数量级。一般来说，需要高浓度的磷脂酰胆碱来重建最大葡萄糖醛酸化活性。本报告证明了人肝中存在多种UDP-葡萄糖醛酸基转移酶。
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