麦芽中脂肪酶活性检测及酶学性质的研究

以乙酸对硝基苯酚酯（p-NPA）为底物,采用对硝基苯酚法测定了麦芽中脂肪酶的活性,并对其酶学性质进行了研究。实验结果表明,麦芽中脂肪酶的最适反应pH为8.5,与5mmol/L的p-NPA的最适反应体积比为1∶7,金属离子Mg2+对麦芽脂肪酶活性有显著的抑制作用,Fe3+、K+则有一定激活作用;该酶热稳定性较强,40℃水浴保温120min,其酶活性几乎保持不变,70℃保温120min后接近失活。麦芽脂肪酶对p-NPA的酶动力学常数Km为0.13mmol/L,Vm值为0.016mg/min。 

Detection of lipase activity in malt and its enzymatic properties research

Taken the 4-nitrophenyl acetate (p-NPA) as the substrate, we detected the activity of lipase in malt and studied its enzymatic properties. Results showed that the optimum pH of lipase activity was 8.5, the optimum reaction volume ratio with 5mmol/L p-NPA was 1∶7, In 10mmol/L the presence of different metal ions Mg2+ could significantly inhibit malt lipase activity and Fe3+、K+ could promote its activity in some degree. The lipase in malt had strong thermostability, it could almost maintain the same activity in 40℃ water bath after 120 minutes and finally became inactivation after 120min in 70℃ water bath preservation. Kinetic constants (Km and Vm) of malt lipase to p-NPA were 0.13mmol/L and 0.016mg/min.