Hochman Y, Zakim D
J Biol Chem. 1983 Apr 10;258(7):4143-6.
Two forms of UDPglucuronyltransferase (EC 2.4.1.17) have been purified from microsomes of pig liver. One form is free of phospholipids and the other contains a small amount of residual phospholipids. Each form, however, is responsive to activation on addition of purified phospholipids. Comparison of kinetic properties of these enzymes, after reconstitution with identical phospholipid environments, indicate that these are unique functional forms of UDPglucuronyltransferase. The two differ by as much as 100-fold in their rates of conjugation at Vm of p-nitrophenol. Relative rates of glucuronidation of a variety of phenolic aglycones are different for the two enzymes, which suggests different reaction mechanisms. The energetic basis for binding of UDP-glucuronic acid to the active sites is different for the two forms of UDPglucuronyltransferase. Moreover, one form, but not the other, binds Mn2+, which leads to modulation of kinetic properties.
已从猪肝微粒体中纯化出两种形式的UDP葡萄糖醛酸转移酶（EC 2.4.1.17）。一种形式不含磷脂，另一种含有少量残留磷脂。然而，每种形式在添加纯化的磷脂后均对激活有反应。在用相同的磷脂环境重构后，对这些酶的动力学特性进行比较，表明它们是UDP葡萄糖醛酸转移酶的独特功能形式。这两种形式在对硝基苯酚的Vm处的结合速率相差多达100倍。两种酶对多种酚类苷元的葡萄糖醛酸化相对速率不同，这表明反应机制不同。两种形式的UDP葡萄糖醛酸转移酶将UDP-葡萄糖醛酸结合到活性位点的能量基础不同。此外，一种形式能结合Mn2+，而另一种则不能，这导致了动力学特性的调节。
