高等学校化学学报 ›› 2021, Vol. 42 ›› Issue (7): 2306.doi: 10.7503/cjcu20210125

• 研究论文 • 上一篇    

人工设计逆醛缩酶RA95.5-8F催化β-羟基酮C—C裂解的理论研究

李心怡, 刘永军()   

  1. 山东大学化学与化工学院, 济南 250100
  • 收稿日期:2021-02-26 出版日期:2021-07-10 发布日期:2021-07-07
  • 通讯作者: 刘永军 E-mail:yongjunliu_1@sdu.edu.cn
  • 基金资助:
    国家自然科学基金(22073056)

Theoretical Insights into the Cleavage of β-Hydroxy Ketone Catalyzed by Artificial Retro-aldolase RA95.5-8F

LI Xinyi, LIU Yongjun()   

  1. School of Chemistry and Chemical Engineering,Shandong University,Jinan 250100,China
  • Received:2021-02-26 Online:2021-07-10 Published:2021-07-07
  • Contact: LIU Yongjun E-mail:yongjunliu_1@sdu.edu.cn
  • Supported by:
    the National Natural Science Foundation of China(22073056)

摘要:

采用量子力学与分子力学组合(QM/MM)方法对人工设计逆醛缩酶RA95.5-8F催化β-羟基酮化合物裂解反应的机理进行了研究. 结果表明, 裂解反应主要包括赖氨酸Lys1083对底物的亲核进攻、 Schiff碱形成、 烯胺水解及C—N断裂等过程, C—N键裂解生成丙酮为整个反应的决速步骤, 能垒为106.27 kJ/mol; 活性中心的赖氨酸Lys1083、 酪氨酸Tyr1051、 天冬酰胺Asn1110和酪氨酸Tyr1180构成一个催化四联体, Lys1083通过与底物形成席夫碱对底物进行活化, Tyr1051作为催化酸碱参与质子转移过程, 催化四联体的氢键网络有利于反应过渡态的稳定并使R-构型的底物更容易结合在活性位点, 导致RA95.5-8F对R构型底物具有高的选择性和催化活性.

关键词: 量子力学与分子力学组合方法, 逆醛缩酶, 酶催化反应, 反应机理

Abstract:

The mechanism of the cleavage of β-hydroxy ketone catalyzed by the artificial retro-aldolase RA95.5-8F was studied by the combined quantum mechanics and molecular mechanics(QM/MM) method. The results show that the cleavage reaction includes the nucleophilic attack of Lys1083 on the substrate, formation of Schiff base intermediate, hydrolysis of enamine, C—N cleavage and so on. The final step of the cleavage of C—N bond to generate acetone is the rate-limiting step with the energy barrier of 106.27 kJ/mol. Lys1083, Tyr1051, Asn1110 and Tyr1180 form a catalytic tetrad, in which Lys1083 and Tyr1051 act as nucleophile and catalytic acid-base, respectively. The hydrogen bond network of the catalytic tetrad stabilizes the reaction transition states and makes it easier for R-configuration substrate to bind to the active site, resul?ting in the high selectivity and reactivity of RA95.5-8F for R-configuration substrate.

Key words: Combined quantum mechanics/molecular mechanics(QM/MM) method, Retro-aldolase, Enzymatic reaction, Reaction mechanism

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