低功率微波耦合溶剂相酶促酯化反应及其荧光光谱的变化

Investigation on Low Power Microwave Irradiation-Assisted Enzymatic Esterification in Organic Solvent by Fluorescence Spectroscopy

以溶剂相脂肪酶LRI催化辛酸和丁醇的酯化反应体系为对象,将反应体系中各组分分别在低功率微波辐射和常规加热下对LRI作用后,用荧光发射光谱分级逐步研究LRI在有机溶剂和水环境中的荧光光谱变化。微波辐射和常规加热在所有实验条件下均增强LRI的荧光强度而没有导致最大发射波长位移。在微波辐射能够提高反应初速度的范围内,当LRI与有机分子共热后,微波辐射更有利于LRI蛋白质分子在水中的裸露。不同logP溶剂的反应体系对酶构象的影响主要表现为溶剂对其的影响。反应初速度对logP的变化规律与水相LRI蛋白质的荧光强度对logP的变化接近,而与溶剂相LRI蛋白质的荧光强度对logP的变化规律之间基本无共同之处。

The authors studied the fluorescence change of immobilized lipase from Rhizomucor rniehei in the microwave assisted enzymatic esterification of caprylic acid and butanol in organic medium by investigating the fluorescence spectra in solvent or aqueous buffer after incubating the lipase with the solvent, caprylic acid and butanol under microwave irradiation, respectively. A comparison was made with the conventional heated enzymatic esterification in the solvents. Both of the heating modes, the microwave irradiation and conventional heating, can enhance the fluorescence intensity without shifting the emission wavelength of the lipase. In the circumstance that the irradiation can accelerate the esterification, the irradiation can enhance the exposure of the lipase protein molecules in the aqueous environment after incubating the lipase with solvents or the substrates. The effect of the reaction mixture on the fluorescence intensity was dominated by the solvents. The trend of the plot of log P versus the initial reaction rate was similar to that of log P versus fluorescence intensity of lipase in aqueous buffer after esterification; but was different from that of log P versus fluorescence intensity of lipase in organic medium.