Sato S, Karasaki Y, Ohno M
J Biochem. 1977 Jul;82(1):231-7. doi: 10.1093/oxfordjournals.jbchem.a131674.
The interaction between alpha-chymotrypsin [EC 3.4.21.1] and peptide substrate or peptide inhibitor was investigated to determine how the secondary interaction influences the rate of hydrolysis or the binding and whether or not its effect is variable with alteration of the P1 residue which interacts with the specificity determining site of the enzyme. Kinetic analysis was carried out at pH 6.5 and 7.8 for substrates of the type Ac-Glyn-X-OMe and for inhibitors of the type Ac-Glyn-X-OH where X denotes tryptophan or its derivatives. With substrates containing tryptophan or Nin-formyltryptophan, the second-order rate of hydrolysis increases with increase of chain length. With substrates containing 2-(2-nitro-4-carboxyphenylsulfenyl)-tryptophan, however, the rate of hydrolysis decreases with elongation of the chain, due to an increase in Km(app). The corresponding inhibitors behave differently from the other series of inhibitors at pH 6.5. The results indicate that the influence of the secondary interaction on reactivity or binding is related to the structural features of the P1 residue.
研究了α-胰凝乳蛋白酶[EC 3.4.21.1]与肽底物或肽抑制剂之间的相互作用，以确定二级相互作用如何影响水解速率或结合，以及其效应是否随与酶的特异性决定位点相互作用的P1残基的改变而变化。在pH 6.5和7.8条件下，对Ac-Glyn-X-OMe类型的底物和Ac-Glyn-X-OH类型的抑制剂进行了动力学分析，其中X表示色氨酸或其衍生物。对于含有色氨酸或N-甲酰基色氨酸的底物，二级水解速率随链长增加而增加。然而，对于含有2-(2-硝基-4-羧基苯亚磺酰基)-色氨酸的底物，由于表观Km增加，水解速率随链的延长而降低。相应的抑制剂在pH 6.5时的行为与其他系列抑制剂不同。结果表明，二级相互作用对反应性或结合的影响与P1残基的结构特征有关。
