Gordon E R, Goresky C A
Can J Biochem. 1980 Nov;58(11):1302-10. doi: 10.1139/o80-175.
Bilirubin transformation in vitro to bilirubin conjugates in the presence of activated rat liver microsomal preparations and UDPglucuronate was assessed with a method involving isolation of the products as tetrapyrroles. The proportions of bilirubin monoglucuronide and diglucuronide formed by the microsomal bilirubin UDPglucuronosyltransferase were found to be governed by the concentration of bilirubin present and the nature of the activation of the microsomal membrane. Activation of the microsomal preparations with the nonionic detergents Triton X-100 or Emulgen 911, or with digitonin for 24 h, produced bilirubin monoglucuronide as the only product at all concentrations of bilirubin investigated. In contrast, bilirubin diglucuronide was the only conjugate formed when hepatic microsomal preparations were activated with digitonin for periods of less tha 2 h and the concentration of bilirubin was 20 microM. Increasing the concentration of bilirubin utilized in this assay system changed the relative amounts of bilirubin monoglucuronide and diglucuronide formed. As the level of bilirubin was increased from 20 to 166 microM, the proportion of bilirubin diglucuronide decreased and that of bilirubin monoglucuronide increased, until at levels of 108 and 166 microM bilirubin only bilirubin monoglucuronide was formed. No evidence was found with liver plasma membranes that transglucuronidation plays a major role in the formation of bilirubin diglucuronide from bilirubin monoglucuronide.
采用一种将产物分离为四吡咯的方法，评估了在活化的大鼠肝微粒体制剂和尿苷二磷酸葡萄糖醛酸存在的情况下胆红素在体外转化为胆红素结合物的情况。发现微粒体胆红素尿苷二磷酸葡萄糖醛酸基转移酶形成的胆红素单葡萄糖醛酸酯和双葡萄糖醛酸酯的比例受胆红素浓度和微粒体膜活化性质的影响。用非离子去污剂吐温X-100或乳化剂911，或用洋地黄皂苷活化微粒体制剂24小时，在所研究的所有胆红素浓度下，仅产生胆红素单葡萄糖醛酸酯作为唯一产物。相比之下，当用洋地黄皂苷活化肝微粒体制剂不到2小时且胆红素浓度为20微摩尔时，胆红素双葡萄糖醛酸酯是唯一形成的结合物。增加该测定系统中使用的胆红素浓度会改变形成的胆红素单葡萄糖醛酸酯和双葡萄糖醛酸酯的相对量。随着胆红素水平从20微摩尔增加到166微摩尔，胆红素双葡萄糖醛酸酯的比例下降，胆红素单葡萄糖醛酸酯的比例增加，直到在108和166微摩尔胆红素水平时仅形成胆红素单葡萄糖醛酸酯。未发现肝细胞膜有证据表明转葡萄糖醛酸化在由胆红素单葡萄糖醛酸酯形成胆红素双葡萄糖醛酸酯中起主要作用。
