Inagaki T, Tadasa K, Kayahara H
Department of Bioscience and Biotechnology, Shinshu University, Nagano, Japan.
Biosci Biotechnol Biochem. 1995 Mar;59(3):535-7. doi: 10.1271/bbb.59.535.
When higher alcoholic solvents were added to the reaction medium, and the enhancement of the enzyme activity, followed by its reduction then inactivation, were observed in thermolysin-catalyzed peptide hydrolysis and synthesis. The organic solvent content used was less than the saturating concentration in the buffer (i.e., water-organic one-phase system). The kinetic parameters, Km and kcat, at the alcoholic concentration giving maximal enzyme activity in these reactions changed linearly with increasing logP values of the alcohols and consequently kcat/Km as well. When the branched isomers of alcohols with structurally minimal variation of which logP was equivalent theoretically, were used as annexments, the kinetic parameters were also changed. The results, especially the changes of Km for each organic solvent, suggested that each alcohol should act at the active site of the enzyme in its own effective mode.
当向反应介质中添加更高浓度的醇类溶剂时，在嗜热菌蛋白酶催化的肽水解和合成反应中，观察到酶活性先增强，随后降低，最终失活。所使用的有机溶剂含量低于缓冲液中的饱和浓度（即水-有机单相体系）。在这些反应中，使酶活性达到最大值的醇浓度下的动力学参数Km和kcat，随醇类logP值的增加呈线性变化，因此kcat/Km也如此。当使用理论上logP值相当但结构变化最小的醇类支链异构体作为添加剂时，动力学参数也会改变。这些结果，尤其是每种有机溶剂的Km变化，表明每种醇应以其自身有效的方式作用于酶的活性位点。
