The structure of a Michaelis serpin-protease complex
The structure of a Michaelis serpin-protease complex
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DOI：
10.1038/nsb1101-979
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发表时间：
2001-11-01
期刊：
影响因子：
--
通讯作者：
Goldsmith, EJ
中科院分区：
文献类型：
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作者：
Ye, S;Cech, AL;Goldsmith, EJ
丝氨酸蛋白酶抑制剂（丝氨酸蛋白酶抑制剂）调节循环蛋白酶的活性。丝氨酸蛋白酶抑制剂通过酰化其活性位点的丝氨酸羟基来抑制蛋白酶。在丝氨酸蛋白酶抑制剂的去酰化和完全蛋白水解可以发生之前，在丝氨酸蛋白酶抑制剂中触发大量构象变化，同时保持蛋白酶和丝氨酸蛋白酶抑制剂之间的共价键。在这里，我们报告的丝氨酸蛋白酶-胰蛋白酶米氏复合物的结构，我们可视化使用S195A胰蛋白酶突变体，以防止共价复合物的形成。这种遭遇复合物揭示了一个更广泛的相互作用表面比目前在小的丝氨酸蛋白酶-蛋白酶复合物，是一个模板，用于建模其他丝氨酸蛋白酶抑制剂-蛋白酶对。在界面处的几个丝氨酸蛋白酶抑制剂残基的突变降低了丝氨酸蛋白酶抑制剂的抑制活性。丝氨酸残基C-末端的易裂的肽键被发现在一个比通常更密切的相互作用与His 57在胰蛋白酶的活性位点。
Serine protease inhibitors (serpins) regulate the activities of circulating proteases. Serpins inhibit proteases by acylating the serine hydroxyl at their active sites. Before deacylation and complete proteolysis of the serpin can occur, massive conformational changes are triggered in the serpin while maintaining the covalent linkage between the protease and serpin. Here we report the structure of a serpin-trypsin Michaelis complex, which we visualized by using the S195A trypsin mutant to prevent covalent complex formation. This encounter complex reveals a more extensive interaction surface than that present in small inhibitor-protease complexes and is a template for modeling other serpin-protease pairs. Mutations of several serpin residues at the interface reduced the inhibitory activity of the serpin. The serine residue C-terminal to the scissile peptide bond is found in a closer than usual interaction with His 57 at the active site of trypsin.