Smith R N, Poindexter T P, Hansch C
Physiol Chem Phys. 1975;7(5):423-36.
A quantitative model for the slow reversible hydrophobic deactivation of alpha-chymotrypsin (alpha-CT) is proposed. Kinetic results are obtained for (1) the situation in which the inhibitor concentration, although remaining constant during the course of a run, can be varied independently of the concentration of nonself-inhibiting substrate, and for (2) the situation in which the self-inhibiting substrate concentration decreases during the course of a run, and independent variation of inhibitor and substrate concentrations is not possible. Excellent quantitative agreement between theory and experiment is obtained for a wide range of conditions using 3-(n-hexanoyl-O-benzoate (with dodecylsulfate as the inhibitor), and 3-(n-decanoyl)-O-benzoate as the self-inhibiting substrate. Activation enthalpies and entropies for the hydrophobic deactivation of alpha-CT by dodecylsulfate and tetradecyltrimethylammonium are determined. For comparison, activation enthalpies and entropies for the alpha-CT hydrolysis of 3-(n-heptanoyl)-O-benzoate are determined; evidence for a thermally induced conformational transition in alpha-CT at 30 degrees C is obtained.
提出了一种用于α-胰凝乳蛋白酶（α-CT）缓慢可逆疏水失活的定量模型。获得了以下两种情况下的动力学结果：（1）抑制剂浓度在实验过程中保持恒定，但可以独立于非自抑制底物的浓度进行变化；（2）自抑制底物浓度在实验过程中降低，且抑制剂和底物浓度不能独立变化。在广泛的条件下，使用3-（正己酰基）-O-苯甲酸酯（以十二烷基硫酸盐作为抑制剂）和3-（正癸酰基）-O-苯甲酸酯作为自抑制底物，理论与实验之间获得了极佳的定量一致性。测定了十二烷基硫酸盐和十四烷基三甲基铵使α-CT疏水失活的活化焓和活化熵。为作比较，测定了3-（正庚酰基）-O-苯甲酸酯被α-CT水解的活化焓和活化熵；获得了在30℃时α-CT中热诱导构象转变的证据。
