Aĭsina R B, Manenkova M A
Biokhimiia. 1982 May;47(5):778-83.
The kinetics of the N-acetyl-L-norvaline methyl ester (non-specific substrate) hydrolysis by trypsin was studied within a wide substrate concentration range (0.02 mM--25.5 mM). The dependence of the initial reaction rate on the substrate concentration obeyed the Michaelis--Menten equation only at low (less than 0.3 mM) concentrations of the substrate. At higher substrate concentrations the reaction rate considerably exceeded the maximal rate determined from the Michaelis--Menten equation. The reaction kinetics at high substrate concentrations was in good agreement with the scheme for the substrate activation of the enzyme proposed by Trowbridge et al. The reaction product, N-acetyl-L-norvaline, did not activate the substrate hydrolysis by trypsin. The kinetic and activation parameters of the reaction (kcat = 0.0184 s-1, Km = 0.08 mM and kcat = 2.97 s-1 and Km = 56 mM, respectively, pH 8.0, 25 degrees) were determined.
在较宽的底物浓度范围（0.02 mM - 25.5 mM）内研究了胰蛋白酶催化N - 乙酰 - L - 正缬氨酸甲酯（非特异性底物）水解的动力学。仅在低底物浓度（小于0.3 mM）时，初始反应速率对底物浓度的依赖性才符合米氏方程。在较高底物浓度下，反应速率大大超过了根据米氏方程确定的最大速率。高底物浓度下的反应动力学与Trowbridge等人提出的酶的底物激活机制相符。反应产物N - 乙酰 - L - 正缬氨酸不会激活胰蛋白酶催化的底物水解。测定了该反应的动力学和活化参数（分别为pH 8.0、25℃时，kcat = 0.0184 s-1，Km = 0.08 mM以及kcat = 2.97 s-1和Km = 56 mM）。
