Schasteen C S, Reed D J
Biochim Biophys Acta. 1983 Jan 26;742(2):419-25. doi: 10.1016/0167-4838(83)90329-1.
Yeast glyoxalase I was inactivated by arginine-specific reagents. Inactivation by 2,3-butanedione, phenylglyoxal and camphorquinone 10-sulfonic acid followed pseudo first-order kinetics with the rate dependent upon modifier concentration. Extrapolation to complete inactivation showed modification of approx. two of the ten total arginyl residues in the native enzyme, with approx. one residue protected by glutathione (GSH) as determined by [ring-14C]phenylglyoxal incorporation. GSH protected the enzyme from inactivation, whereas methylglyoxal, glutathione disulfide (GSSG) and dithiothreitol afforded partial protection. The hemimercaptal of methylglyoxal and GSH and the catalytic product, S-lactoylglutathione provided substantial protection from inactivation. A methyl ester placed on the glycyl carboxyl moiety of GSH abolished all protective capability which suggests that this functionality is responsible for binding to the enzyme. These results provide the first evidence concerning the molecular binding mode of GSH to an enzyme. Arginyl residues are proposed as anionic recognition sites for glutathione on other GSH-utilizing enzymes.
酵母乙二醛酶I可被精氨酸特异性试剂灭活。2,3 - 丁二酮、苯乙二醛和樟脑醌10 - 磺酸导致的失活遵循假一级动力学，其速率取决于修饰剂浓度。外推至完全失活表明，天然酶中总共十个精氨酰残基中有约两个被修饰，通过[环 - 14C]苯乙二醛掺入法测定，约有一个残基受到谷胱甘肽（GSH）的保护。GSH可保护该酶不被灭活，而甲基乙二醛、谷胱甘肽二硫化物（GSSG）和二硫苏糖醇提供部分保护。甲基乙二醛与GSH的半硫醇加合物以及催化产物S - 乳酰谷胱甘肽提供了对失活的显著保护。在GSH的甘氨酰羧基部分上放置一个甲酯消除了所有保护能力，这表明该官能团负责与酶结合。这些结果提供了关于GSH与酶分子结合模式的首个证据。精氨酰残基被认为是其他利用GSH的酶上谷胱甘肽的阴离子识别位点。
