米曲霉蛋白酶动力学特性的研究

Study on Kinetic Behaviors of Aspergillus oryzae Protease

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。

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 bc 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 Mg^2＋ and inhibited by EDTA, SDS, Zn^2＋, Mn^2＋ or Sn^2＋ obviously, however it is not affected by 10 mmol/L H2O2.