催化学报

催化学报 ›› 2008, Vol. 29 ›› Issue (2): 141-144.

• 研究论文 • 上一篇    下一篇

脂肪酶催化乳酸与乙醇合成乳酸乙酯的反应动力学

赵天涛1,2,3,张丽杰1,高静2,黄志红2,全学军1   

  1. 1 重庆工学院生物工程学院, 重庆 400050; 2 河北工业大学化工学院, 天津 300130; 3 同济大学环境科学与工程学院, 上海 200092
  • 收稿日期:2008-02-25 出版日期:2008-02-25 发布日期:2012-01-15

Reaction Kinetics of Ethyl Lactate Synthesis from Lactic Acid and Ethanol Catalyzed by Lipase

ZHAO Tiantao1,2,3, ZHANG Lijie1, GAO Jing2*, HUANG Zhihong2, QUAN Xuejun1   

  1. 1 School of Bioengineering, Chongqing Institute of Technology, Chongqing 400050, China; 2 School of Chemical Engineering, Hebei University of Technology, Tianjin 300130, China; 3 School of Environmental Science and Engineering, Tongji University, Shanghai 200092, China
  • Received:2008-02-25 Online:2008-02-25 Published:2012-01-15

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1194

被引次数

34

摘要： 对脂肪酶催化乳酸与乙醇合成乳酸乙酯反应的动力学进行了研究,根据乒乓机制和双底物抑制的特性建立了反应速率方程. 反应时间常数(tR)和扩散时间常数(tD)的计算结果表明,酯化反应速率未受到明显的限制. 反应速率方程可以很好地预测实验结果,由非线性拟合得到的动力学参数中,乳酸(A)和乙醇(B)的抑制常数分别为KiA=10.7 mmol/L和KiB=275.0 mmol/L. 这说明乳酸作为短链极性脂肪酸,对酶的失活作用远大于乙醇. 乳酸在微液层中聚集并产生了使酶失活的低pH值环境,同时在酯化反应中存在竞争性抑制作用.

关键词: 反应动力学, 脂肪酶, 酶催化, 乳酸, 乙醇, 乳酸乙酯, 竞争性抑制, 扩散限制

Abstract: The reaction kinetics of lipase-catalyzed esterification of lactic acid and ethanol was studied. The reaction rate could be described in terms of a ping-pong bi-bi mechanism and double-substrate inhibition. No evidence of any diffusion limitation that affected the kinetics was detected by the comparison between the time constants for the reaction (tR) and diffusion (tD). The predicted values of the corresponding mechanism reaction fitted the experimental data very well, and the rate constants were obtained by non-linear fitting analysis. The inhibition constants for lactic acid (A) and ethanol (B) were KiA=10.7 mmol/L and KiB=275.0 mmol/L, respectively, which suggested that lactic acid, being a short-chain polar acid, caused the enzyme inactivation more seriously than ethanol. The lactic acid was concentrated in the micro-aqueous layer and caused a pH drop, leading to the enzyme inactivation in its microenvironment, and the competitive inhibition of enzyme by lactic acid existed during the lipase-catalyzed esterification reaction.

Key words: reaction kinetics, lipase, enzyme catalysis, lactic acid, ethanol, ethyl lactate, competitive inhibition, diffusion limitation