尿苷二磷酸葡糖醛酸基转移酶的磷脂依赖性。豚鼠肝微粒体酶的磷脂耗竭与再激活。
The phospholipid-dependence of uridine diphosphate glucuronyltransferase. Phospholipid depletion and re-activation of guinea-pig liver microsomal enzyme.
作者信息
Graham A B, Pechey D T, Toogood K C, Thomas S B, Wood G C
出版信息
Biochem J. 1977 Apr 1;163(1):117-24. doi: 10.1042/bj1630117.
More than 80% of the phospholipid component of guinea-pig liver microsomal membranes (prepared with 154mM-KCl) was removed by treatment with phospholipase A followed by extraction of the lysophosphatides and fatty acids produced with albumin. Delipidation strongly inactivated the highly active UDP-glucuronyltransferase of these preparations and activity was restored by mixtures of phosphatidylcholine and lysophosphatidylchlone. However, small quantities of lysophosphatides were still associated with the delipidated fractions after extraction with albumin and might have influenced the inactivation and re-activation observed. To eliminate these uncertainties, microsomal proteins and phospholipids were separated by gel filtration on Sephadex G-150 in the presence of cholate. This technique also strongly inactivated the enzyme but did not generate membrane-active phospholipid degradation products. High transferase activity was again restored to the delipidated protein by choline glycerophosphatides. These results confirm the view that the fully active form of microsomal UDP-glucuronyltransferase is phospholipid-dependent.
用磷脂酶A处理豚鼠肝微粒体膜（用154mM - KCl制备），然后用白蛋白提取产生的溶血磷脂和脂肪酸，可去除其磷脂成分的80%以上。脱脂强烈地使这些制剂中高活性的UDP - 葡萄糖醛酸转移酶失活，而磷脂酰胆碱和溶血磷脂酰胆碱的混合物可恢复其活性。然而，在用白蛋白提取后，少量的溶血磷脂仍与脱脂部分相关联，可能影响了观察到的失活和重新激活。为消除这些不确定性，在胆酸盐存在下，通过Sephadex G - 150凝胶过滤分离微粒体蛋白和磷脂。该技术也强烈地使酶失活，但不会产生具有膜活性的磷脂降解产物。胆碱甘油磷脂可再次使脱脂蛋白恢复高转移酶活性。这些结果证实了微粒体UDP - 葡萄糖醛酸转移酶的完全活性形式依赖于磷脂这一观点。
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