Peisach E, Wang J, de los Santos T, Reich E, Ringe D
Program in Biophysics and Structural Biology, Brandeis University, Waltham, Massachusetts 02454-9110, USA.
Biochemistry. 1999 Aug 24;38(34):11180-8. doi: 10.1021/bi991130r.
We have solved the X-ray crystal structure of the proenzyme form of the catalytic domain of plasminogen, with the nonessential mutations M585Q, V673M, and M788L, to 2.0 A resolution. The structure presents an inactive protease characterized by Asp740 (chymotrypsinogen 194) hydrogen bonded to His586 (chymotrypsinogen 40), preventing proper formation of the oxyanion hole and S1 specificity pocket. In addition, the catalytic triad residues are misplaced relative to the active conformation adopted by serine proteases in the chymotrypsin family. Finally, a unique form of zymogen inactivation is observed, characterized by a "foot-in-mouth" mechanism in which Trp761 (chymotrypsinogen 215) is folded into the S1 specificity pocket preventing substrate binding.
我们已经解析了纤溶酶原催化结构域前酶形式（带有非必需突变M585Q、V673M和M788L）的X射线晶体结构，分辨率达到2.0埃。该结构呈现出一种无活性的蛋白酶，其特征为天冬氨酸740（胰凝乳蛋白酶原194）与组氨酸586（胰凝乳蛋白酶原40）形成氢键，从而阻止了氧阴离子洞和S1特异性口袋的正常形成。此外，催化三联体残基相对于胰凝乳蛋白酶家族中丝氨酸蛋白酶所采用的活性构象位置不当。最后，观察到一种独特的酶原失活形式，其特征为“口含足”机制，即色氨酸761（胰凝乳蛋白酶原215）折叠进入S1特异性口袋，阻止底物结合。
