米曲霉蛋白酶动力学特性的研究

研究了在不同底物浓度、温度和pH下米曲霉蛋白酶水解酪蛋白产生酪氨酸的动力学特性。在反应时间为10min时,最佳反应温度为50℃,最佳反应pH为9。实验表明米曲霉蛋白酶水解酪蛋白生成酪氨酸的反应符合米氏方程,根据实验数据回归得到温度为40℃时的速度方程为r=0.243CS/0.0282+CS,反应速度与氢离子浓度的关系为r=lgCH++3.14013/0.19759+0.05484(lgCH++3.14013)+(lgCH++3.14013)2。该蛋白酶在50℃下的失活规律符合双指数模型,相对酶活力与时间的关系为a=0.82531e(-0.02169t)+0.17469e(-0.41914t)。在4～50℃的范围内,蛋白酶水解反应的活化能Ea为30.67kJ。还研究了不同化学组分对蛋白酶活力的影响,发现10mmol/L的H3BO3和Mg2+对该蛋白酶有一定的激活作用,而EDTA、SDS、Zn2+、Mn2+和Sn2+对蛋白酶有明显的抑制作用,10mmol/L的H2O2对该蛋白酶的抑制作用不明显。

Study on Kinetic Behaviors of Aspergillus oryzae Protease

The kinetic behaviors of casein hydrolysis by Aspergillus oryzae protease were studied under different substrate concentrations, temperatures and pHs. The optimal temperature and pH for 10 min-reactions are: 50 ℃ and pH 9 respectively. The experiment results showed that at 40 ℃, the kinetics of casein hydrolysis by the protease fit the Mchaelis-Menton equation which can be written as r=0.243CS/0.0282+CS and the relation between hydrolysis rate and hydrogen ion concentration is: r=lgCH++3.14013/0.19759+0.05484(lgCH++3.14013)+(lgCH++3.14013)2. The protease relative deactivity at 50 ℃ follows a= 0.82531e(-0.02169t)+0.17469e(-0.41914t). The energy of activation (Ea) under 50℃ is 30.67 kJ. The effects of different chemicals on protease activity were observed under the same condition as protease activity assay. The protease activity is enhanced by 10 mmol/L H3BO3 or Mg2+ and inhibited by EDTA, SDS, Zn2+, Mn2+ or Sn2+ obviously, however it is not affected by 10 mmol/L H2O2.