Narindrasorasak S, Bridger W A
Can J Biochem. 1978 Aug;56(8):816-9. doi: 10.1139/o78-124.
Phosphoenolpyruvate synthetase of Escherichia coli is strongly inhibited by oxalate. The magnitude of the inhibition constant for oxalate suggests that this compound acts to produce a transition state analogue, in keeping with the suggestion of others that oxalate mimics the structure of enolpyruvate, a presumed catalytic intermediate in the enzymatic reaction. The addition of oxalate together with ATP results in a dramatic shielding of sensitive amino acid residues from reaction with both N-ethyl maleimide and phenylglyoxal. Thus, under conditions otherwise giving rise to almost complete inactivation by either reagent, no loss of activity is detectable in the presence of oxalate and ATP. These results indicate the formation of an enclosed structure during catalysis in which reactive groups are rendered quite inaccessible to solvent.
大肠杆菌的磷酸烯醇丙酮酸合成酶受到草酸盐的强烈抑制。草酸盐抑制常数的大小表明，该化合物起到产生过渡态类似物的作用，这与其他人的观点一致，即草酸盐模拟了烯醇丙酮酸的结构，烯醇丙酮酸是酶促反应中假定的催化中间体。草酸盐与ATP一起添加会导致敏感氨基酸残基与N-乙基马来酰亚胺和苯乙二醛的反应受到显著屏蔽。因此，在其他条件下两种试剂几乎会导致完全失活的情况下，在草酸盐和ATP存在时未检测到活性丧失。这些结果表明在催化过程中形成了一种封闭结构，其中反应基团对溶剂相当不可达。
