Tian W X, Tsou C L
Biochemistry. 1982 Mar 2;21(5):1028-32. doi: 10.1021/bi00534a031.
On the basis of the equations derived previously [Tsou, C. L. (1965) Sheng Wu Hua Hsueh Yu Sheng Wu Wu Li Hsueh Pao 5, 398-408, 409-417] for the substrate reaction during the course of enzyme modification, the kinetic behavior of the system chymotrypsin-substrate-modifier has been studied. The kinetics of benzoyltyrosine ester hydrolysis during the course of irreversible inhibition of the enzyme has been found to be in satisfactory agreement with equations obtained previously. The apparent rate constant between the enzyme and an irreversible inhibitor can be easily obtained in one single experiment by following the course of substrate hydrolysis in the presence of the inhibitor. The results are also in accord with the assumption that diisopropyl fluorophosphate can be classified as an irreversible competitive inhibitor. For both phenylmethanesulfonyl fluoride and L-1-[(p-toluene-sulfonyl)amino]-2-phenylethyl chloromethyl ketone, the inhibition has been found to be in agreement with the kinetics of the complexing type; i.e., a noncovalent enzyme-inhibitor complex is formed before irreversible enzyme modification. Both the equilibrium constants for the complex formation and the first-order rate constants for the irreversible modification step have been determined also by following the course of substrate hydrolysis in the presence of the irreversible inhibitor.
基于先前推导的方程[邹承鲁（1965年），《生物化学与生物物理学报》5, 398 - 408, 409 - 417]，研究了在酶修饰过程中底物反应的情况，对胰凝乳蛋白酶 - 底物 - 修饰剂体系的动力学行为进行了研究。发现在酶的不可逆抑制过程中苯甲酰酪氨酸乙酯水解的动力学与先前得到的方程符合得很好。通过在抑制剂存在下跟踪底物水解过程，在单次实验中就能轻松得到酶与不可逆抑制剂之间的表观速率常数。结果也符合将氟磷酸二异丙酯归类为不可逆竞争性抑制剂的假设。对于苯甲磺酰氟和L - 1 - [(对甲苯磺酰基)氨基]-2 - 苯乙基氯甲基酮，已发现抑制作用符合络合类型的动力学；即，在酶进行不可逆修饰之前会形成非共价的酶 - 抑制剂复合物。通过在不可逆抑制剂存在下跟踪底物水解过程，还测定了复合物形成的平衡常数以及不可逆修饰步骤的一级速率常数。
