α-淀粉酶热稳定剂及失活动力学研究

Study on thermal stabilizer of α-amylase and its inactivation kinetic

α-淀粉酶在高温条件下半衰期短,易失活,提高其热稳定性的方法有:添加稳定剂、化学修饰、固定化等.研究了加入热稳定剂醋酸钙、乳酸钠后α-淀粉酶的热稳定性及失活动力学,测定了半衰期(t1/2)、失活速率常数(k)、活化能(Ea)等参数.结果表明,在α-淀粉酶中加入0.01 mol/L醋酸钙后,80℃酶的半衰期(t1/2)从<1.8 min提高到89.9 min,加入0.02 mol/L乳酸钠后提高到167.1 min,大大提高了α-淀粉酶的热稳定性;未加热稳定剂的淀粉酶失活动力学符合一级反应(R2>0.99);添加热稳定剂后酶的失活动力学发生变化,但失活中后期符合一级反应(R2>0.98).

α-amylase has short half-life time and is easy to be inactive. The methods to improve its thermal stability were： adding thermal stabilizer, chemical modification, immobilization etc. Thermal stability of α-amylase and inactivation kinetic was studied after the addition of thermal stabilizer calcium acetate and sodium lactate. Half-life time （t1/2）, inactivation rate constant （k） and activation energy （Ea） were determined to characterize the effect of thermal stabilizers. The results showed that half-life is increased from less than 1.8 min to 89.9 min with 0.01 mol/L of calcium acetate addition and to 167.1 min with 0.02 mol/L of sodium lactate addition at 80 %, the thermostability of the enzyme Was greatly enhanced. The inactivation kinetic of amylase without stabilizer accorded to the first order reaction （R^2〉0.99）. The inactivation kinetic of amylase with stabilizer changed and accorded to the first order reaction （R^2〉0.98） at the late stage of inactivation.