Interindividual variability in acetaminophen glucuronidation by human liver microsomes: identification of relevant acetaminophen UDP-glucuronosyltransferase isoforms.
Interindividual variability in acetaminophen glucuronidation by human liver microsomes: identification of relevant acetaminophen UDP-glucuronosyltransferase isoforms.
复制标题
DOI：
--
复制
发表时间：
2001-12
期刊：
影响因子：
--
通讯作者：
M. Court;S. Duan;L. Moltke;D. Greenblatt;C. Patten;J. Miners;P. Mackenzie
中科院分区：
文献类型：
--
作者：
M. Court;S. Duan;L. Moltke;D. Greenblatt;C. Patten;J. Miners;P. Mackenzie
对乙酰氨基酚（APAP）糖醛酸化的个体间差异可能导致人类对APAP中毒的易感性差异。本研究的目的是鉴定在人肝微粒体（HLMs）中介导APAP-UGT活性的相关udp -葡萄糖醛酸糖基转移酶（UGT）亚型。利用56个供体和9个重组人ugt的hla检测APAP-UGT活性和酶动力学。用20只肝脏定量测定UGT1A1、UGT1A4、UGT1A9和UGT2B7介导的活性以及UGT1A6的相对蛋白含量。肝微粒体APAP-UGT活性变化超过15倍，且呈低活性分布。虽然大多数ugt都能使APAP葡糖苷化，但UGT1A1、UGT1A6和UGT1A9最具活性。UGT1A6是相对高亲和力（K(m) = 2.2 mM）、低容量的酶；UGT1A1在亲和力（K(m) = 9.4 mM）和容量上处于中间水平；UGT1A9为低亲和力（K(m) = 21 mM）、高容量酶。高活性和中活性HLMs （6-10 mM）的K(m)值与UGT1A1相似，低活性HLMs （10-55 mM）的K(m)值与UGT1A9相似。APAP-UGT活性与异丙酚- ugt （r = 0.85; UGT1A9）和胆红素- ugt （r = 0.66; UGT1A1）活性相关性最好，但与UGT1A6蛋白活性相关性较差（r = 0.30）。在临床相关的APAP浓度范围（50微米至5毫米）内，建立了一个动力学模型，确定UGT1A9是HLMs中主要的APAP- ugt（总活性55%）。在毒性浓度下，UGT1A1也有很大的贡献（>为1 mM， >为28%的活性），而UGT1A6在相对较低的浓度下最具活性（29%的活性）。
Interindividual variability in acetaminophen (APAP) glucuronidation may contribute to differences in susceptibility to APAP intoxication in humans. The purpose of this study was to identify the relevant UDP-glucuronosyltransferase (UGT) isoforms mediating APAP-UGT activity in human liver microsomes (HLMs). APAP-UGT activities and enzyme kinetics were determined using HLMs from 56 donors and nine recombinant human UGTs. Activities mediated by UGT1A1, UGT1A4, UGT1A9, and UGT2B7, and relative UGT1A6 protein content were quantified using 20 livers. More than 15-fold variation in liver microsomal APAP-UGT activities was observed with a distribution skewed toward lower activities. Although most UGTs could glucuronidate APAP, UGT1A1, UGT1A6, and UGT1A9 were most active. UGT1A6 was a relatively high-affinity (K(m) = 2.2 mM), low-capacity enzyme; UGT1A1 was intermediate in affinity (K(m) = 9.4 mM) and capacity; and UGT1A9 was a low-affinity (K(m) = 21 mM), high-capacity enzyme. K(m) values were similar to UGT1A1 in high- and intermediate-activity HLMs (6-10 mM) and UGT1A9 in low-activity HLMs (10-55 mM). APAP-UGT activities correlated best with propofol-UGT (r = 0.85; UGT1A9) and bilirubin-UGT (r = 0.66; UGT1A1) activities, but poorly with UGT1A6 protein (r = 0.30). A kinetic model was constructed from these data that identified UGT1A9 as the predominant APAP-UGT (>55% total activity) in HLMs over a clinically relevant APAP concentration range (50 microM-5 mM). UGT1A1 was also predicted to contribute substantially at toxic concentrations (>1 mM; >28% activity), whereas UGT1A6 was most active at relatively low concentrations (29% activity).