Mechanistic Insight into the Inactivation of Carboxypeptidase A by α-Benzyl-2-oxo-1,3-oxazolidine-4-acetic Acid, a Novel Type of Irreversible Inhibitor for Carboxypeptidase A with No Stereospecificity
作者:Sang J. Chung、Suhman Chung、Hyun Soo Lee、Eun-Jung Kim、Kyung Seok Oh、Hyuk Soon Choi、Kwang S. Kim、Yeoun Jin Kim、Jong Hoon Hahn、Dong H. Kim
DOI:10.1021/jo010421e
日期:2001.9.1
stereospecificity shown in the inactivation led us to propose that the ring cleavage occurs by the nucleophilic attack at the 2-position rather than at the 5-position and the ring opening takes place in an addition-elimination mechanism. The tetrahedral transition state that would be generated in this pathway is thought to be stabilized by the active site zinc ion, which was supported by the PM3 semiemprical calculations
根据羧肽酶A(CPA)的活性位点拓扑结构和酶催化机制,原型为含锌的蛋白水解酶,α-苄基-2-氧代-1,3-恶唑烷-4-乙酸(1)为被设计为一种新型的基于机制的酶灭活剂。从光学活性的天冬氨酸开始,以对映体纯的形式合成了抑制剂的所有四种可能的立体异构体,并对它们的CPA抑制活性进行了评估,发现令人惊讶的是,所有四种立体异构体均以时间依赖性方式抑制了CPA。透析后,抑制的酶没有恢复其酶活性。灭活被2-苄基琥珀酸阻止,后者是一种竞争性抑制剂,已知能与酶的活性位点结合。这些动力学结果强烈支持灭活剂在活性位点共价附于酶。对失活的CPA的ESI质谱数据进行分析,从动力学结果可以得出结论。二阶抑制率常数(k(obs)/ [I](o))的值在1.7-3.6 M(-1)min(-1)的范围内。失活中缺乏立体定向性,导致我们提出环裂解是通过亲核攻击在2位而不是5位发生的,开环发生在加成消除机理中。认为该途径将产