Rush G F, Hook J B
Life Sci. 1984 Jul 9;35(2):145-53. doi: 10.1016/0024-3205(84)90133-4.
Rat renal microsomes catalyzed the glucuronidation of l-naphthol, 4-methylumbelliferone and p-nitrophenol, whereas morphine and testosterone conjugation were not detected. In contrast, all five substrates were conjugated by hepatic microsomes; the activity was typically 5-10 times greater than with renal microsomes. Renal microsomal UDP-glucuronyltransferase toward l-naphthol was fully activated (six-fold) by 0.03% deoxycholate while the hepatic enzyme was fully activated (eight-fold) by 0.05% deoxycholate. Full activation of hepatic UDP-glucuronyltransferase occurred when microsomes had been preincubated at 0 C with deoxycholate for 20 min. This effect of preincubation was not observed with renal microsomes. The presence of 0.25M sucrose in the buffers during renal microsomal preparation resulted in a two-fold greater rate of l-naphthol conjugation in both unactivated and activated microsomes than renal microsomes prepared in phosphate buffers alone. Preparation of hepatic microsomes with or without 0.25M sucrose had no effect on UDP-glucuronyltransferase activity. Unactivated (-deoxycholate) renal enzyme was activated when incubations were done at a low pH (5.7), whereas fully activated (0.03% deoxycholate) renal microsomal UDP-glucuronyltransferase displayed a pH optimum at 6.5. Renal microsomal UDP-glucuronyltransferase activity toward l-naphthol, p-nitrophenol and 4-methylumbelliferone was induced by pretreatment of rats with beta-naphthoflavone and trans-stilbene oxide but not by phenobarbital or 3-methylcholanthrene. These data demonstrate that renal UDP-glucuronyltransferases are different from the hepatic enzymes with regard to biochemical properties, substrate specificity and in response to chemical inducers of xenobiotic metabolism.
大鼠肾微粒体可催化 1-萘酚、4-甲基伞形酮和对硝基苯酚的葡萄糖醛酸化反应，而未检测到吗啡和睾酮的结合反应。相比之下，所有这五种底物均可被肝微粒体结合；其活性通常比肾微粒体高 5 至 10 倍。肾微粒体对 1-萘酚的 UDP-葡萄糖醛酸基转移酶被 0.03%的脱氧胆酸盐完全激活（激活 6 倍），而肝酶则被 0.05%的脱氧胆酸盐完全激活（激活 8 倍）。当微粒体在 0℃下与脱氧胆酸盐预孵育 20 分钟时，肝 UDP-葡萄糖醛酸基转移酶会完全激活。肾微粒体未观察到这种预孵育的效果。在肾微粒体制备过程中，缓冲液中存在 0.25M 蔗糖，导致在未激活和激活的微粒体中，1-萘酚结合反应的速率比仅在磷酸盐缓冲液中制备的肾微粒体快两倍。用或不用 0.25M 蔗糖制备肝微粒体对 UDP-葡萄糖醛酸基转移酶活性没有影响。未激活的（-脱氧胆酸盐）肾酶在低 pH（5.7）条件下孵育时会被激活，而完全激活的（0.03%脱氧胆酸盐）肾微粒体 UDP-葡萄糖醛酸基转移酶在 pH 6.5 时表现出最佳活性。用β-萘黄酮和反式氧化茋预处理大鼠可诱导肾微粒体对 1-萘酚、对硝基苯酚和 4-甲基伞形酮的 UDP-葡萄糖醛酸基转移酶活性，但苯巴比妥或 3-甲基胆蒽则不能。这些数据表明，肾 UDP-葡萄糖醛酸基转移酶在生化特性、底物特异性以及对外源生物代谢化学诱导剂的反应方面与肝酶不同。
