Fournel-Gigleux S, Shepherd S R, Carre M C, Burchell B, Siest G, Caubere P
Centre du Médicament, Unité de recherche associée 597, Centre National de la Recherche Scientifique, Nancy, France.
Eur J Biochem. 1989 Aug 15;183(3):653-9. doi: 10.1111/j.1432-1033.1989.tb21095.x.
The in vitro inhibitory potency of 20 structurally related alkanoic and arylalkanoic acids has been investigated on rat liver UDP-glucuronosyltransferase. These compounds were tested on the microsomal and purified enzyme, and a cloned cDNA expressed in COS 7 cell cultures. Among all the acids tested, 7,7,7-triphenylheptanoic acid was the most powerful inhibitor of bilirubin:UDP-glucuronosyltransferase with a lower effect on 1-naphtol, androsterone and testosterone glucuronidation. The inhibition was competitive towards the microsomal and purified bilirubin:UDP-glucuronosyltransferases with Kiapp values of 12.0 microM and 1.6 microM, respectively. Twenty analogues were examined, and the results showed that their inhibitory potency on bilirubin:UDP-glucuronosyltransferase activity was a function of at least three structural features (a) the presence of a hydrophobic triphenyl moiety; (b) the length of the aliphatic chain and (c) the presence of a carboxylic group. These inhibitors were also tested as possible substrates of UDP-glucuronosyltransferases. The strongest inhibitors were poor substrates of rat liver microsomal UDP-glucuronosyltransferases. However, 7,7,7-triphenylheptanoic acid was actively glucuronidated by purified bilirubin:UDP-glucuronosyltransferase, in contrast to its analogues with decreasing alkyl chain length. In addition, glucuronidation of this molecule was enhanced by clofibrate treatment but could not be detected in Gunn rats, which are deficient in bilirubin:UDP-glucuronosyltransferase, further indicating that the glucuronidation of this compound was catalysed by bilirubin:UDP-glucuronosyltransferase. The results suggest that 7,7,7-triphenylheptanoic acid may be a useful structural probe to investigate the molecular basis of glucuronidation of bilirubin and carboxylic acids.
已研究了20种结构相关的链烷酸和芳基链烷酸对大鼠肝脏UDP-葡萄糖醛酸基转移酶的体外抑制效力。这些化合物在微粒体和纯化酶以及在COS 7细胞培养物中表达的克隆cDNA上进行了测试。在所有测试的酸中，7,7,7-三苯基庚酸是胆红素：UDP-葡萄糖醛酸基转移酶最有效的抑制剂，对1-萘酚、雄甾酮和睾酮葡萄糖醛酸化的影响较小。该抑制作用对微粒体和纯化的胆红素：UDP-葡萄糖醛酸基转移酶具有竞争性，其表观解离常数（Kiapp）值分别为12.0微摩尔和1.6微摩尔。研究了20种类似物，结果表明它们对胆红素：UDP-葡萄糖醛酸基转移酶活性的抑制效力至少取决于三个结构特征：（a）疏水性三苯基部分的存在；（b）脂肪链的长度；（c）羧基的存在。这些抑制剂还作为UDP-葡萄糖醛酸基转移酶的可能底物进行了测试。最强的抑制剂是大鼠肝脏微粒体UDP-葡萄糖醛酸基转移酶的不良底物。然而，与烷基链长度递减的类似物相反，7,7,7-三苯基庚酸可被纯化的胆红素：UDP-葡萄糖醛酸基转移酶积极地葡萄糖醛酸化。此外，氯贝丁酯处理可增强该分子的葡萄糖醛酸化，但在缺乏胆红素：UDP-葡萄糖醛酸基转移酶的Gunn大鼠中未检测到，这进一步表明该化合物的葡萄糖醛酸化是由胆红素：UDP-葡萄糖醛酸基转移酶催化的。结果表明，7,7,7-三苯基庚酸可能是研究胆红素和羧酸葡萄糖醛酸化分子基础的有用结构探针。
