GLUCURONIDATION OF 3'-AZIDO-3'-DEOXYTHYMIDINE IN HUMAN LIVER-MICROSOMES - ENZYME-INHIBITION BY DRUGS AND STEROID-HORMONES
GLUCURONIDATION OF 3'-AZIDO-3'-DEOXYTHYMIDINE IN HUMAN LIVER-MICROSOMES - ENZYME-INHIBITION BY DRUGS AND STEROID-HORMONES
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DOI：
10.1016/0925-4439(92)90077-z
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发表时间：
1992-06-09
期刊：
影响因子：
--
通讯作者：
SIEST, G
中科院分区：
文献类型：
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作者：
HERBER, R;MAGDALOU, J;SIEST, G
在人肝微粒体中表征了参与3 '-叠氮基-3'-脱氧胸苷（AZT）-5 '-O-葡糖苷酸催化的UDP-葡糖苷酸转移酶的分子形式。比活性（1.3 nmol/min每毫克蛋白质）在可移植的肝脏是2倍以上，高于死后的片段。患有Crigler-Najjar综合征的患者的肝微粒体也可以使AZT葡萄糖醛酸化，这表明这种蛋白质不参与该过程，这些患者在遗传上缺乏胆红素UDP-葡萄糖醛酸转移酶。稳定表达编码对1-萘酚有活性的人同工酶的cDNA的基因工程V79细胞系不能使AZT葡萄糖醛酸化。临床使用的药物，其中大多数是葡萄糖醛酸化的，被测试为人肝微粒体中AZT葡萄糖醛酸化的潜在抑制剂。化学上与2-苯基丙酸、萘普生和氟比洛芬相关的药物以及类固醇化合物睾酮、雌酮和乙炔雌二醇强烈抑制AZT葡萄糖醛酸化。可待因和吗啡也降低反应速率，但程度较低。除雌酮引起部分竞争性抑制外，乙炔基布洛芬、氟比洛芬、萘普生和睾酮均能竞争性抑制AZT葡萄糖醛酸化，表观K（i）分别为38、50、172和250 μ M。结果表明，这些药物是参与AZT葡萄糖醛酸化的相同同工酶的底物。丙磺舒是一个弱抑制剂的反应（K（i）900 μ M），只有当非破坏微粒体被使用。该药物可能与参与微粒体摄取UDP-葡萄糖醛酸的阴离子载体系统竞争。
The molecular form of UDP-glucuronosyltransferase involved in the catalysis of 3'-azido-3'-deoxythymidine (AZT)-5'-O-glucuronide was characterized in human liver microsomes. The specific activity (1.3 nmol/min per mg protein) in transplantable liver was more than 2-times higher than in post-mortem fragments. Liver microsomes from patients suffering Crigler-Najjar syndrome, who are genetically deficient in bilirubin UDP-glucuronosyltransferase, could also glucuronidate AZT to a similar extent, thus indicating that this protein was not involved in that process. A genetically engineered V79 cell line stably expressing a CDNA which encodes a human isozyme active towards 1-naphthol was unable to glucuronidate AZT. Clinically used drugs, most of them being glucuronidated, were tested as potential inhibitors of the glucuronidation of AZT in human liver microsomes. The drugs chemically related to 2-phenylpropionic acid, naproxen and flurbiprofen, and the steroid compounds testosterone, estrone and ethynylestradiol strongly inhibited AZT glucuronidation. Codeine and morphine also decreased the reaction rate although to a lower extent. Except estrone which ellicited a partial competitive inhibition, ethynylestradiol, flurbiprofen naproxen and testosterone could competitively inhibit AZT glucuronidation with an apparent K(i) of 38, 50, 172 and 250-mu-M, respectively. The results suggest that these drugs were substrates of the same isozyme(s) involved in AZT glucuronidation. Probenecid was a weak inhibitor of the reaction (K(i) 900-mu-M), only when non-disrupted microsomes were used. This drug may compete with the anion carrier system involved in the microsomal uptake of UDP-glucuronic acid.