大戟叶大戟中的二聚体丝氨酸蛋白酶——瑞香狼毒素S：纯化及生化特性研究
Neriifolin S, a dimeric serine protease from Euphorbia neriifolia Linn.: Purification and biochemical characterisation.
作者信息
Yadav Ravi Prakash, Patel Ashok Kumar, Jagannadham M V
机构信息
Molecular Biology Unit, Institute of Medical Sciences, Banaras Hindu University, Varanasi 221005, India.
Molecular Biology Unit, Institute of Medical Sciences, Banaras Hindu University, Varanasi 221005, India.
出版信息
Food Chem. 2012 Jun 1;132(3):1296-1304. doi: 10.1016/j.foodchem.2011.11.107. Epub 2011 Dec 1.
A dimeric serine protease Neriifolin S of molecular mass 94kDa with milk clotting activity has been purified from the latex of Euphorbia neriifolia by anion exchange and size-exclusion chromatography. It hydrolyses peptidyl substrates l-Ala-pNA with highest affinity (K of 0.195mM) and physiological efficiency (K/K of 144.5mMs). Enzyme belongs to the class of neutral proteases with pI value of 6.8, optimal proteolytic activity displayed at pH 9.5 and temperature 45°C. Its proteolytic activity is strongly stimulated in the presence of Ca ions and exclusively inhibited by serine protease inhibitors. Enzyme is fairly stable toward chemical denaturants, pH and temperature. The apparent T, was found to be 65°C. Thermal inactivation follow first order kinetics with activation energy (Ea), activation enthalpy (ΔH∗), free energy change (ΔG∗) and entropy (ΔS∗) of 27.54kJmol, 24.89kJmol, -82.34kJmol and 337.20JmolK.
已通过阴离子交换和尺寸排阻色谱法从大戟科植物麻风树的乳胶中纯化出一种具有凝乳活性、分子量为94 kDa的二聚体丝氨酸蛋白酶Neriifolin S。它以最高亲和力（K为0.195 mM）和生理效率（K/K为144.5 mM s）水解肽基底物l-Ala-pNA。该酶属于中性蛋白酶类别，其pI值为6.8，在pH 9.5和温度45°C时表现出最佳蛋白水解活性。其蛋白水解活性在钙离子存在下受到强烈刺激，并且仅被丝氨酸蛋白酶抑制剂抑制。该酶对化学变性剂、pH和温度相当稳定。发现其表观熔点为65°C。热失活遵循一级动力学，活化能（Ea）、活化焓（ΔH∗）、自由能变化（ΔG∗）和熵（ΔS∗）分别为27.54 kJ mol、24.89 kJ mol、-82.34 kJ mol和337.20 J mol K。
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