Béchet J J, Dupaix A, Blagoeva I
Biochimie. 1977;59(3):231-9. doi: 10.1016/s0300-9084(77)80139-9.
alpha-Chymotrypsin is rapidly and completely inactivated by a series of halomethylated derivatives of dihydrocoumarins at pH 7 and 25 degrees. The inactivation is pH-dependent and optimal at neutral pH; it is also more or less complete depending on the excess of inhibitor with respect to the enzyme. These compounds are substrates for alpha-chymotrypsin and, during the catalytic process, a latent alkylating function of the reagent is activated at the active site of the enzyme and reacts with some vicinal nucleophilic amino acid residues. The stoichiometry of the reaction of the corresponding radioactive reagents with the enzyme is slightly superior to one, but one histidine residue of alpha-chymotropsin is mainly modified. This histidine is identified as histidine-57 by the diagonal peptide mapping method. In comparison with other reagents, the efficiency of these suicide substrates" and particularly that one of a derivative (compound 2) carrying a substrate-like side chain is found to be very high.
在pH 7和25摄氏度条件下，α-胰凝乳蛋白酶可被一系列二氢香豆素的卤甲基化衍生物迅速且完全地灭活。这种灭活作用依赖于pH值，在中性pH时最为有效；根据抑制剂相对于酶的过量程度，灭活作用或多或少是完全的。这些化合物是α-胰凝乳蛋白酶的底物，在催化过程中，试剂的潜在烷基化功能在酶的活性位点被激活，并与一些相邻的亲核氨基酸残基发生反应。相应放射性试剂与酶反应的化学计量比略高于1，但α-胰凝乳蛋白酶的一个组氨酸残基主要被修饰。通过对角线肽图谱法将该组氨酸鉴定为组氨酸-57。与其他试剂相比，发现这些“自杀底物”的效率，特别是带有底物样侧链的一种衍生物（化合物2）的效率非常高。
