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

Reaction Processes of Lipid-coated Enzymes in Supercritical Fluids

超临界流体中脂质包被酶的反应过程

基本信息

批准号：
11450311
负责人：
OKAHATA Yoshio
金额：
$ 9.09万
依托单位：
TOKYO INSTITUTE OF TECHNOLOGY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B).
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

项目摘要

Supercritical fluids (scFs) have been attractive as media for enzymatic reactions, as well as other chemical reactions and media for extraction. Because their physical properties can be manipulated by small changes in pressure and temperature, and several of these properties (e.g., density, diffusiveness, and viscosity) are intermediate between those of gas and liquid. The larger diffusiveness in scF compared to a liquid can be expected to increase the reaction rate.In this report, we report the high catalytic activity of a lipid-coated b-galactosidase for transgalactosylation to alcohols in supercritical fluorofolm (scCHF3). Typical results are stummarized in the figure. A lipid-coated b-galactosidase can catalyse the transgalactosylation from p-nitrophenyl galactopyranoside to 5-phenylpentanol in sufficient efficiency in organic solvents, however the enzyme easily denatured and both the initial rate νo and the conversion decreased drastically in polar solvents above chloroform (the left figure). On the contrary, in the supercritical CHF3, the νo of the reaction increased 20 times compared with those in organic solvents (the right figure). The νo could be reversibly controlled by changing the pressure of supercritical fluid from 1 to 150 atm, and the conversion was almost constant, This means that the reactivity of a lipid-coated enzyme cam be reversibly controlled without denaturation in supercritical fluid by changing pressure (polarity). This is the first example to control enzyme reactions in supercritical fluids.

超临界流体（scFs）作为酶促反应的介质以及用于提取的其他化学反应和介质已经是有吸引力的。因为它们的物理性质可以通过压力和温度的微小变化来操纵，并且这些性质中的几个（例如，密度、扩散性和粘度）介于气体和液体之间。与液体相比，在超临界流体中更大的扩散性可以预期增加反应速率。在这份报告中，我们报告了高催化活性的脂质涂层的b-半乳糖苷酶在超临界fluorofolm（scCHF 3）中转半乳糖基化为醇。典型的结果在图中示出。脂质包被的β-半乳糖苷酶可以在有机溶剂中以足够的效率催化从对硝基苯基吡喃半乳糖苷到5-苯基戊醇的转半乳糖基化，然而该酶容易变性，并且在氯仿以上的极性溶剂中初始速率ν 0和转化率都急剧下降（左图）。相反，在超临界CHF 3中，反应的νo比在有机溶剂中增加了20倍（右图）。通过改变超临界流体的压力（1 ~ 150 atm），可以可逆地控制V0，并且转化率几乎是恒定的。这意味着通过改变压力（极性），可以可逆地控制脂质包被酶的反应性，而不发生变性。这是在超临界流体中控制酶反应的第一个例子。