权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Enzyme Activity and Its Application in Non-aqueous Solvents

酶活性及其在非水溶剂中的应用

基本信息

批准号：
63470068
负责人：
KISE Hideo
金额：
$ 3.26万
依托单位：
Tsukuba University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1988
资助国家：
日本
起止时间：
1988 至 1989
项目状态：
已结题

项目摘要

The synthetic reactions of amino acid esters and peptides by the catalysis of proteases in hydrophilic (water-miscible) organic solvents were investigated. Attention has been focused on kinetic aspects of these reactions and the effects of immobilization of the enzymes on their catalytic activity and substrate- and stereo-specificities.The results are summarized as follows: Serine proteases, such as alpha-chymotrypsin, subtilisin BPN', and subtilisin Carlsberg, exhibited catalytic activity for ester synthesis, transesterification, and peptide synthesis. in many of hydrophilic organic solvents which have been considered to deactivate enzymes. Especially subtilisin Carlsberg retains high activity in aqueous ethanol in which the enzyme dissolves. The reaction rate and product yield depend strongly on the nature of solvent, especially water concentration; maximum rate and yield were obtained at water concentration below 10%. The reactions exhibited Michaelis- Menten kinetics, and the kindtic parameters suggest that the rate determining steps for ester synthesis and transesterification are acylation and deacylation of the enzyme, respectively. Furthermore, the reduction of hydrophobic interaction between the enzyme and substrate was suggested compared to that in aqueous solutions. The change in substrate specificity, especially the specificity of amine components, was shown for peptide synthesis in organic solvents.The large increase in catalytic activity of enzymes was realized by the immobilization to specific support materials, such as chitin, chitosan, and PVA-chitosan blend films.The results may be interpreted not only by concentration of substrates around the enzymes, but also by activity enhancement of the enzymes by adsorption to the supports.The results indicate the possibility of controlling enzyme activity and specificity by the selection of media and support materials.

研究了在亲水性（水溶性）有机溶剂中蛋白酶催化氨基酸酯和氨基酸肽的合成反应。注意力一直集中在这些反应的动力学方面和固定化的酶对它们的催化活性和底物和立体specificity. Results的影响，总结如下：丝氨酸蛋白酶，如α-胰凝乳蛋白酶，枯草杆菌蛋白酶BPN '，和枯草杆菌蛋白酶嘉士伯，表现出催化活性的酯合成，酯交换，和肽合成。在许多被认为是使酶失活的亲水性有机溶剂中。特别是枯草杆菌蛋白酶Carlsberg在酶溶解的含水乙醇中保持高活性。反应速率和产率强烈地依赖于溶剂的性质，特别是水的浓度;当水的浓度低于10%时，获得最大速率和产率。该反应符合米氏动力学，动力学参数表明酯合成和酯交换反应的速率控制步骤分别是酶的酰化和脱酰化。与水溶液相比，酶与底物之间的疏水相互作用减弱。结果表明，在有机溶剂中，酶对底物的专一性，特别是对胺组分的专一性发生了变化，酶被固定在特定的载体材料上，如甲壳素、壳聚糖和PVA-壳聚糖共混膜上，酶的催化活性大大提高，这不仅与酶周围底物的浓度有关，结果表明，通过选择合适的载体和介质，可以控制酶的活性和专一性。