Ringe D, Mottonen J M, Gelb M H, Abeles R H
Biochemistry. 1986 Sep 23;25(19):5633-8. doi: 10.1021/bi00367a043.
The inactivation of chymotrypsin by 3-benzyl-6-chloro-2-pyrone has been studied. A covalent adduct is formed that deacylates slowly with a half-life of 23 h. X-ray diffraction analysis at 1.9-A resolution of the inactivator-enzyme complex shows that the gamma-oxygen of the active-site serine (serine-195) is covalently attached to C-1 of (Z)-2-benzylpentenedioic acid, the benzyl group of the inactivator is held in the hydrophobic specificity pocket of the enzyme, and the free carboxylate forms a salt bridge with the active-site histidine (histidine-57). The conformational changes that occur in the protein as a result of complexation are described. It is proposed that formation of the salt bridge prevents access of water and, therefore, hydrolysis of the acyl-enzyme.
对3-苄基-6-氯-2-吡喃酮使胰凝乳蛋白酶失活的过程进行了研究。形成了一种共价加合物，其脱酰化过程缓慢，半衰期为23小时。对失活剂-酶复合物进行1.9埃分辨率的X射线衍射分析表明，活性位点丝氨酸（丝氨酸-195）的γ-氧与（Z）-2-苄基戊烯二酸的C-1共价连接，失活剂的苄基位于酶的疏水特异性口袋中，游离羧酸盐与活性位点组氨酸（组氨酸-57）形成盐桥。描述了由于形成复合物而在蛋白质中发生的构象变化。有人提出，盐桥的形成阻止了水的进入，因此也阻止了酰基酶的水解。
