中文摘要：

报道了α-糜蛋白酶（α-CT）催化活性及其与阳离子双子表面活性剂（N，N＇-双（十二烷基二甲基）-1，2-二溴化癸二铵，简写为12-10-12）相互作用热力学的关系。酶活性通过紫外-可见吸收光谱法测量底物醋酸2-萘酯（2-NA）分解速率进行评估。在较短的培育时间内，12-10．12能够激活α-CT，得到催化2-NA分解的超活性，同时也加速了酶变性的动力学过程。在低于α-CT／12-10-12体系的临界聚集浓度（cac12-10-12CT）时，显示一个钟形的大的超活性区。酶活性随时间变化的结果表明，由12-10-12激活的α-CT有高的酶活性和低的变性稳定性。进而采用等温滴定量热（ITC）、稳态荧光光谱和差示扫描量热（DSC）技术研宄了12-10-12诱导α-CT超活性的机理。结果表明酶的超活性来源于正电荷的12-10-12与α-CT相互作用对α-CT内部结构的扰动，使得酶的构象变得比处于弱相互作用平衡的天然酶的构象更加松弛，这有利于2-NA水解酸性产物释放的动力学，而同时也导致了α-CT结构的不稳定性。

英文摘要：

This work presents the correlation of the enzymatic activity of α-chymotrypsin （a-CT） with the thermodynamics of interaction between α-CT and the cationic gemini surfactant decanediyl-α, α-bis （dodecyldimethylammonium bromide） （12-10-12）. The enzymatic activity was assessed by the rate of 2-naphthyl acetate （2-NA） hydrolysis obtained from UV-Vis absorption spectra. The superactivity of α-CT in the catalytic hydrolysis of 2-NA was obtained by activation with 12-10-12 in a short incubation time; the activated α-CT showed faster denaturation kinetics. The larger superactivities appeared in a bell shape below the critical aggregation concentration （cac12-10-12,CT） of the mixed gemini/α-CT systems in buffered aqueous solution. The results obtained from the variation of the activity with the incubation time highlight that the protein incubated in 12-10-12 has a high catalysis activity and a weakened conformational stability. The mechanism of the superactivity of α-CT in the presence of 12-10-12 has been proposed by combining the results from isothermaltitration calorimetry （ITC）, steady state fluorescence, and differential scanning calorimetry （DSC）. The superactivity arises from perturbation of the internal structure of α-CT by an interaction between the positively charged 12-10-12 and α-CT, which makes the conformation of α-CT looser than the native one, in the balance of a weak interaction. Such a conformation is favorable for release of the acidic product of 2-NA hydrolysis, whereas it simultaneously leads to instability of the α-CT structure.