微波辐射下双酶催化淀粉水解的动力学研究

以玉米淀粉为反应底物,研究了α-淀粉酶和糖化酶分别在微波辐射和水浴加热条件下水解玉米淀粉的动力学特性。考察了pH、温度、底物质量浓度、酶用量对玉米淀粉水解反应速率的影响。结果表明,微波辐射条件下的平均反应速率比水浴加热提高了20%以上。以米氏方程为基础,研究了两种加热方式下的米氏常数Km、最大反应速率νm和抑制常数Ki。结果表明,微波辐射下α-淀粉酶的Km=3 922.76 g/L,νm=1.72×10-3mol/(mL.min),糖化酶的Km=173.31 g/L,νm=3.289×10-5mol/(mL.min);水浴加热条件下α-淀粉酶的Km=312.03g/L,νm=1.21×10-4mol/(mL.min),糖化酶的Km=16.14 g/L,νm=3.89×10-6mol/(mL.min);微波辐射下糖化酶的抑制常数(Ki)低于水浴加热的抑制常数。

Kinetics of Corn Starch Hydrolysis by Enzyme Catalysis Under Microwave Irradiation

The kinetics of the corn starch hydrolysis catalyzed by α-amylase and glucoamylase in microwave irradiation,comparing with the water bath heating,was studied.The effects of pH value,reaction temperature,substrate concentration,the amount of α-amylase and glucoamylase on the initial reaction velocity were investigated.It is showed that the initial velocity of the starch hydrolysis in microwave irradiation is about 20% more than that obtained by the water bath heating.Based on the Michealis equation,the Michealis constant Km,the maximum reaction velocity νm and the inhibition constant Ki were investigated.In the microwave irradiation,the K_m and ν_m of the starch hydrolysis catalyzed by α-amylase are 3 922.76 g/L and 1.72×10-3 mol/(mL·min),and the K_m and ν_m by glucoamylase are 173.31 g/L and 3.289×10~(-5) mol/(mL·min).While by the water bath heating,the K_m and ν_m of the starch hydrolysis catalyzed by α-amylase are 312.03 g/L and 1.21×10~(-4) mol/(mL·min),and the K_m and ν_m by glucoamylase are 16.14 g/L and 3.89×10~(-6) mol/(mL·min).The inhibition constant of glucoamylase in the microwave irradiation is less than that by the water bath heating.