蛋白酶在乙醇溶液中的性质及构象

The Properties and Conformation of Proteases in Ethanol Solution

对碱性蛋白酶和木瓜蛋白酶在乙醇溶液中的性质和构象进行了研究。研究结果表明,在乙醇溶液中,碱性蛋白酶和木瓜蛋白酶催化反应的最适温度有不同程度下降,下降幅度为5～10℃;它们的最适pH与在缓冲液体系中相差不大。2种蛋白酶在醇溶液中的稳定性随着乙醇浓度的升高而下降,特别是当乙醇浓度上升至60%,2种蛋白酶的稳定性均迅速下降。在相同的乙醇浓度下,木瓜蛋白酶的稳定性比碱性蛋白酶高。当乙醇浓度为60%时,木瓜蛋白酶的半衰期是碱性蛋白酶的21倍。圆二色谱研究表明,在乙醇溶液中碱性蛋白酶和木瓜蛋白酶的二级结构均发生了明显变化,荧光光谱表明,在乙醇溶液中2种蛋白酶的荧光强度均有明显减弱,表明它们的三级结构均发生明显变化。

The properties and conformation of alkaline protease and papain in ethanol solutions were researched. The results showed that the optimum temperature of alkaline protease and papain in ethanol solutions were reduced with the increase of ethanol concentration. The range of temperature descent was 5 - 10℃. The optimum pH in ethanol solutions had little difference comparing with buffer solution. With the increase of ethanol concentration, the stability of alkaline protease and papain were affected. Especially, when the concentration of ethanol solutions was up to 60% , the stability of alkaline protease and papain decreased rapidly. The stability of papain was higher than alkaline protease in the same ethanol concentration and the half-life of papain was 21 times of alkaline protease in 60% etha- nol. The Circular dichroism spectra of the protease in ethanol solutions showed that the secondary structure of alkaline protease and papain were altered seriously. The Fluorescence spectra of the protease ethanol solution indicated that the fluorescence intensity of alkaline protease and papain in ethanol solutions were both weakened. These results confirmed that in ethanol solution the tertiary structure of those protease were changed obviously.