Departments of Pure and Applied Chemistry & Bioscience and Biotechnology, University of Strathclyde, 295 Cathedral Street, Glasgow, G1 1XL UK.
Biotechnol Bioeng. 1997 Jul 20;55(2):278-82. doi: 10.1002/(SICI)1097-0290(19970720)55:2<278::AID-BIT5>3.0.CO;2-F.
A carboxylic acid functionalized dendritic polybenzyl ether has been synthesized and used with its sodium salt to generate a novel acid/base buffer soluble in nonpolar organic solvents. The effect of different ratios of the two buffer forms on the catalytic activity of subtilisin Carlsberg and chymotrypsin was investigated in toluene. It was found that reproducible transesterification rates were obtained at each molar ratio consistent with a buffering effect. As the molar ratio of the sodium salt to acid was increased there was a corresponding increase in the catalytic activity of both enzymes although their profiles were not identical. This is consistent with a requirement for deprotonation of a residue at active site of the enzyme as observed in aqueous solution. The ability to alter and precisely control the ionization state of biocatalysts in nonpolar solvents may find useful applications for both fundamental studies and in syntheses where reactants or products have acid/base properties. (c) 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 55: 278-282, 1997.
一种羧酸官能化树枝状聚苄基醚已被合成，并与它的钠盐一起使用，生成一种新型的在非极性有机溶剂中可溶解的酸碱缓冲剂。考察了两种缓冲形式的不同比例对枯草杆菌蛋白酶和糜蛋白酶在甲苯中的催化活性的影响。结果发现，在与缓冲作用一致的每个摩尔比下，都可以得到可重复的转酯化速率。尽管两种酶的图谱并不相同，但随着钠盐与酸的摩尔比的增加，两种酶的催化活性都相应增加。这与在水溶液中观察到的酶活性部位的残基去质子化的要求一致。在非极性溶剂中改变和精确控制生物催化剂的离解状态的能力，可能会在基础研究和反应物或产物具有酸碱性质的合成中找到有用的应用。（c）1997 年 John Wiley & Sons，Inc.《生物工程学报》55:278-282，1997。
