具有光学活性的羧基肽酶—A抑制剂的设计合成及动力学研究

【作者】 玄伟；

【导师】 田官荣；

【作者基本信息】 延边大学 ， 有机化学， 2007， 硕士

【摘要】 本文根据羧基肽酶-A（CPA）最新研究进展，基于CPA的活性部位及作用机理设计了具有光学活性的新型抑制剂（±，R-，S-）-2-苄基-5-溴-4-氧戊酸（A）、（±，R-，S-）-2-苄基-4-氧戊酸（B），进一步探讨了CPA中各个活性部位间的相互作用。2-苄基-5-溴-4-氧戊酸和2-苄基-4-氧戊酸的光学异构体都是以重氮酮作为主要中间体来合成的。动力学测试结果表明，它们对CPA有不同的抑制作用，（R）-A的抑制效果比（S）-A强260倍，（R）-B的抑制效果比（S）-B强11倍，通过旋光值的测定证实（R）-A型是属于L型系列，从（R）-A抑制效果来看，它应该是一种过渡态类似抑制剂，（R）-B应该是一种底物类似抑制剂。测试结果表明在酮的α位引入溴能大大提高羰基的亲核性，2-苄基-5-溴-4-氧戊酸形成偕二醇的形式很好的模拟了CPA催化过程中的四面体过渡态，能够和CPA的活性部位紧紧结合，这应该是（R）-A抑制作用强的最合理解释。此外，以红景天立枯病菌（Rhizoctonia solani Kuhn）等12种病原真菌为供试靶标，我们合成了胡桃醌（5-羟基-1，4-萘醌）及其衍生物5，8-二羟基-1，4-萘醌。农学院测试了它们的抑菌活性结果表明：两者对丝核菌属病原真菌菌丝生长的抑制作用大于镰刀属，对3种丝核菌属病原真菌的EC₅₀分别为10.63～15.88mg／L、9.79～14.69mg／L；两者对玉米小斑病菌孢子萌发的抑制作用最高，在12.5mg／L时，抑制率均达到60％以上，对镰刀属4种病原真菌孢子萌发，在50mg／L时，抑制率均达到60％。更多还原

【Abstract】 Compounds A,B,were designed as irreversible inhibitor to explore the interactionsof the active site of CPA according to the latest research progresses and themechanism of CPA. Both enantiomers of 2-benzyl-5-bromo-4-oxopentanoic acid Aand 2-benzyl-4-oxopentanoic acid B were prepared utilizing the diazo ketones as thekey intermediates and all of them assayed for inhibitory activity againstcarboxypeptidase A to find that the （R）-forms are more potent than theircorresponding enantiomers, i.e., 260-fold for A and 11-fold for B, respectively. Thefinding that the （R）-A which belongs to the L-series is mostly responsible for theinhibitory activity accords with the explanation that it is a transition state analoginhibitor. In the other hand, the more than 120-fold weak inhibition ofcarboxypeptidase A by （R）-B suggested that the non-halogenated ketone should be asubstrate analog inhibitor of carboxypeptidase A. These results further disclosed thatthe introduction of bromo group at the a-position of ketones could significantlyenhance the electrophilicity of the carbonyl group and the generated gem-diol form ofA in situ, which mimics the transition state in the catalytic process, should beresponsible for the potent inhibition of carboxypeptidase A.The antifungal activities of Juglone and its derivative,5,8-dihydroxy-1,4-naphtho- quinine, were tested against 12 pathogenic fungi. Bothcompounds shown the higher inhibition effects on the growth of mycelial ofRhizoctonia pathogeny compared to the case of Fusarium. oxysporum f. sp.. The EC₅₀values of Juglone and 5,8-dihydroxy-1,4-naphthoquinine against three fungi ofRhizoctonia pathogeny were 10.63-15.88mg/L and 9.79-14.69mg/L, respectively.Both of them exhibited the highest inhibitory effects on conidial germination toBipolaris maydis and, which were determined as 60% at the concentrations of 12.5mg/L. For conidial germination of the four kinds of pathogenic fungi ofFusarium.oxysporum f. sp., their inhibitory rate can be about 60 % at the dosage of 50mg/L.更多还原