Patston P A, Schapira M
Department of Oral Medicine and Diagnostic Sciences, University of Illinois-Chicago 60612, USA.
Biochem Biophys Res Commun. 1997 Jan 23;230(3):597-601. doi: 10.1006/bbrc.1996.6010.
Serpins inhibit proteinases by a branched pathway, in which an intermediate serpin-proteinase complex can either form a stable covalent serpin-proteinase complex or produce reactive center cleaved serpin in a substrate reaction. It was tested whether these competing reactions could be regulated for the serpin C1-inhibitor by ligand binding. C1-inhibitor bound to type IV collagen, laminin, and entactin. Type IV collagen (10 microg/ml) caused an increase in the stoichiometry of inhibition for C1s inhibition by C1-inhibitor to 1.48 from 1.09 in the absence of ligand. A dose-dependent increase in the stoichiometry up to 1.27 in the presence of 100 microg/ml heparin was also observed. At low ionic strength the stoichiometry increased to 2.55. These data provide the first report that C1-inhibitor can bind to type IV collagen and also show that C 1-inhibitor can be regulated by ligand binding.
丝氨酸蛋白酶抑制剂（Serpins）通过一条分支途径抑制蛋白酶，在该途径中，丝氨酸蛋白酶抑制剂 - 蛋白酶中间复合物既可以形成稳定的共价丝氨酸蛋白酶抑制剂 - 蛋白酶复合物，也可以在底物反应中产生反应中心裂解的丝氨酸蛋白酶抑制剂。研究了配体结合是否可以调节丝氨酸蛋白酶抑制剂C1 - 抑制剂的这些竞争反应。C1 - 抑制剂与IV型胶原、层粘连蛋白和巢蛋白结合。IV型胶原（10微克/毫升）使C1 - 抑制剂对C1s抑制的抑制化学计量比从无配体时的1.09增加到1.48。在存在100微克/毫升肝素的情况下，也观察到化学计量比呈剂量依赖性增加，最高可达1.27。在低离子强度下，化学计量比增加到2.55。这些数据首次报道了C1 - 抑制剂可以与IV型胶原结合，也表明C1 - 抑制剂可以通过配体结合进行调节。
