菠萝蛋白酶催化大豆蛋白水解反应的热动力学

Thermodynamic Studies on Catalytic Reaction Between Bromelain and Soybean Protein

利用热活性检测仪测定了菠萝蛋白酶催化大豆蛋白水解反应的热功率-时间曲线,按照热动力学理论和对比进度法解析出不同温度、酸度时菠萝蛋白酶催化大豆蛋白水解反应的米凯利斯常数(K m)和最大速率(V max),并建立了K m与温度和酸度的关系式,从而获得酶催化反应的最适温度(314.63 K)和最适pH(6.99).在最适温度和最适pH条件下,测定了金属离子可逆竞争时菠萝蛋白酶催化大豆蛋白水解反应的热功率-时间曲线,对曲线进行处理,得到了酶催化反应的米凯利斯常数(K'm)和最大速率(V'max).建立了K'm与金属离子浓度间的关系式,比较了金属离子对酶催化反应的激活或抑制效果.

The power-time curves of reaction between bromelain and soybean protein were determined using microcalorimeter. Using the thermodynamic theory and reduced extent method, the Michaelis constant （Km ） and the maximum velocity （ limax） of catalytic reaction were obtained at different temperatures and pH values, and the equations from the relation between Km and temperatures（Km-T） , and pH values（Km-pH） were estab- lished. Based on the established equations, the optimum temperature （314.63 K） and the optimum pH （6. 99） were gained. Under the optimum temperature and pH, the power-time curves of catalytic reaction with metal ions were obtained, and the apparent Michaelis constant（K ） and the maximum reaction velocity（ Vmax ） were gained Km and Vmax . The relations between the K and the contents of metal ions were established. Compared with the , the activation or inhibition effect of metal ions on enzymatic reaction could be known.