【摘要】 目的:研究猪胰脂肪酶(porcine pancreas lipase,PPL)在丙二醇单相共溶体系中催化橄榄油水解反应的活性变化及其作用机理。方法:测定PPL在不同体积浓度的丙二醇溶液中催化橄榄油水解的活性、动力学参数变化及紫外光谱、紫外差示光谱、荧光光谱的变化情况。结果:体积分数为17%的丙二醇使PPL活性提高了55%;丙二醇处理后,PPL的vmax基本不变,而Km值则明显下降;光谱分析发现,经丙二醇处理后,PPL的紫外吸收光谱发生蓝移,而紫外差示光谱则出现了两个明显的负峰,荧光发射峰强度显著降低。结论:体积分数为17%的丙二醇对PPL有一定的激活作用,该激活作用可能是由于在丙二醇溶液中PPL发生构型和构象的变化,提高了酶分子对底物的亲和力,从而引起酶活性的升高。更多还原

【Abstract】 Objective: This investigation is to study the variation of porcine pancreas lipase(PPL) activity in propylene glycol solution,and the action mechanism of propylene glycol on the enzyme. Method: Different concentrations of propylene glycol were added into the reaction system of olive-oil hydrolysis to test the catalytic activity,kinetics and molecular spectra of PPL.Result:It was indicated that hydrolysis activity of PPL was increased by 55% when the system contained 17% propylene glycol.When PPL was treated with propylene glycol,the vmax remained unchanged while Km value declined.Furthermore,in 17% propylene glycol the ultraviolet absorption spectrum of PPL appeared hypsochromic shift and the differential ultraviolet spectrum showed two negative peaks,and the fluorescent emission intensity weakened obviously.Conclusion: It can be concluded that PPL could be activated by propylene glycol at low concentration.The activation effect of propylene glycol on this enzyme was possibly caused by the changes of PPL configuration and conformation to increase the appetency of PPL to the substrate of the enzyme.更多还原