Haribabu B, Rao N A, Vaidyanathan C S
Biochem Int. 1985 Dec;11(6):773-80.
4-Hydroxyisophthalate hydroxylase was inactivated by treatment with phenylglyoxal by a process obeying pseudo-first order kinetics indicating the presence of an essential arginine located presumably in the active site. Addition of saturating amounts of 4-hydroxyisophthalate during the treatment resulted in complete protection of the enzyme from the inactivation, but addition of NADPH was totally ineffective. Analysis of the effect of various substrate analogs on the protection of the enzyme showed that carboxyl and hydroxyl groups at para positions on the aromatic ring are essential for substrate binding to the active site. It was also observed that analogs which protect the enzyme against phenylglyoxal inactivation are themselves effective inhibitors of the enzyme activity.
用苯乙二醛处理使4-羟基间苯二甲酸羟化酶失活，该过程遵循假一级动力学，表明可能在活性位点存在一个必需的精氨酸。在处理过程中加入饱和量的4-羟基间苯二甲酸可使酶完全免受失活影响，但加入NADPH则完全无效。分析各种底物类似物对酶保护作用的影响表明，芳香环对位的羧基和羟基对于底物与活性位点的结合至关重要。还观察到，能保护酶免受苯乙二醛失活的类似物本身就是酶活性的有效抑制剂。
