Ascenzi P, Amiconi G, Coletta M, Lupidi G, Menegatti E, Onesti S, Bolognesi M
Department of Pharmaceutical Chemistry and Technology, University of Turin, Italy.
J Mol Biol. 1992 May 5;225(1):177-84. doi: 10.1016/0022-2836(92)91034-m.
Thermodynamic parameters for the binding of hirudin to human alpha, beta and gamma-thrombin have been determined between pH 5.0 and 9.0, and from 10 degrees C to 40 degrees C; kinetic data for the association and dissociation of the proteinase-inhibitor complex were obtained at pH 7.5 and 21 degrees C. These results have been analysed in parallel with the inhibitor-binding properties of human alpha, beta and gamma-thrombin for the bovine basic pancreatic trypsin inhibitor (Kunitz-type inhibitor; BPTI). For the purpose of an homogeneous comparison, values of the apparent association equilibrium constant for BPTI binding to human gamma-thrombin have been determined between pH 5.0 and 9.0, at 21 degrees C. The different binding behaviour of hirudin and BPTI with respect to human alpha, beta and gamma-thrombin has been related to the inferred stereochemistry of the proteinase-inhibitor contact regions. In particular, whereas the beta and gamma-loops play an appreciable role in the stabilization of the enzyme-hirudin complexes, they contribute to impairment of the adduct formation for the proteinase/BPTI system.
已测定了在pH 5.0至9.0之间以及10℃至40℃范围内水蛭素与人α、β和γ凝血酶结合的热力学参数；在pH 7.5和21℃下获得了蛋白酶-抑制剂复合物缔合和解离的动力学数据。这些结果已与人类α、β和γ凝血酶对牛碱性胰蛋白酶抑制剂（库尼茨型抑制剂；BPTI）的抑制剂结合特性进行了平行分析。为了进行均匀比较，已测定了在21℃下pH 5.0至9.0之间BPTI与人γ凝血酶结合的表观缔合平衡常数的值。水蛭素和BPTI与人α、β和γ凝血酶不同的结合行为已与蛋白酶-抑制剂接触区域的推断立体化学相关。特别是，虽然β环和γ环在酶-水蛭素复合物的稳定中起显著作用，但它们导致蛋白酶/BPTI系统加合物形成受损。
