无溶剂及微乳液体系中脂肪酶催化红花油水解的动力学

Kinetics of Lipase-Catalyzed Safflower Oil Hydrolysis in Solvent-Free and Microemulsion Media

在无溶剂及二(2-乙基己基)丁二酸酯磺酸钠(AOT)/异辛烷/磷酸盐缓冲液微乳液体系中,研究了黑曲霉脂肪酶催化红花油水解反应的动力学.结果表明,无溶剂及微乳液体系中反应的活化能分别为32.205和7.391kJ/mol.酶在无溶剂体系中的热稳定性高于微乳液中.无溶剂及微乳液体系中的表观米氏常数分别为0.135和0.101mol/L.在两种体系中,乙醇对水解反应的抑制作用均为竞争性可逆抑制,且均在底物浓度大于0.819mol/L时出现底物抑制现象.

The kinetics of safflower oil hydrolysis catalyzed by a lipase from Aspergillus niger was investigated in a solvent-free medium and an AOT/isooctane/phosphate buffer microemulsion medium. The activation energy of the reaction was calculated from the Arrhenius plot to be 32.205 and 7. 391 kJ/mol in the solvent-free medium and the microemulsion medium, respectively. The denaturation of the lipase in microemulsion was faster than that in the solvent-free medium. The apparent Michaelis constant Km was 0. 135 mol/L in the solvent-free medium and 0. 101 mol/L in the microemulsion medium. The experiment indicated that the inhibition of alcohol towards the lipase was reversible and competitive in both the solvent-free medium and the microemulsion medium. In addition, the inhibition by substrate appeared in these two systems when the substrate concentration exceeded 0. 819 mol/L. The micelle catalysis theory and ester bond hydrolysis mechanism were used to explain the difference of lipase-catalyzed oil hydrolysis in the solvent-free medium and the microemulsion medium.