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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。
Using corn starch as reaction substrate, the kinetics of hydrolysis of corn starch by α-amylase and saccharifying enzyme under microwave irradiation and water bath heating were studied. The effects of pH, temperature, substrate concentration and enzyme dosage on the hydrolysis rate of corn starch were investigated. The results show that the average reaction rate under microwave irradiation is more than 20% higher than that of water bath heating. Based on the Mie equation, the Michaelis constant Km, the maximum reaction rate νm and the inhibition constant Ki under two heating methods were studied. The results showed that the Km value of α-amylase under microwave irradiation was 3 922.76 g / L, νm = 1.72 × 10-3mol / (mL.min), Km of glucoamylase was 173.31 g / L, νm was 3.289 × 10-5mol (mL.min); Km = 312.03g / L, νm = 1.21 × 10-4mol / (mL.min), α-amylase Km = 16.14g / L, νm = 3.89 × 10-6mol / (mL · min). The inhibition constant (Ki) of saccharifying enzyme under microwave irradiation was lower than that of water bath.