摘要
考察了酵母醇脱氢酶在“水／气溶胶ＯＴ／有机溶剂”逆胶束系统中催化脂肪醇氧化反应的条件、性能及动力学。结果表明，在构成逆胶束连续相的各种有机溶剂中，疏水性越强则酶的活力越高，以异辛烷为最佳。逆胶束中酶反应的最适温度在２５℃左右；活化能约为５２ｋＪ／ｍｏｌ，比水相系统略低。逆胶束酶的活力随着系统的含水量Ｒ增加而升高，但应控制Ｒ＜５０，以不出现相变混浊为限。酶活力与ｐＨ的关系与底物醇的浓度有关，仅在浓度很低（［ｓ］＜Ｋｍ）时才呈现极值位于ｐＨ８．２的钟形曲线，一般在浓度较高时酶活力随ｐＨ增大而单调上升。酶在逆胶束中的底物特异性不同于普通的水相系统；正丁醇为最适底物，其表观米氏常数为３．３０ｍｍｏｌ／Ｌ，低于水溶液中的４．３４ｍｍｏｌ／Ｌ。
The catalytic conditions,performance and kinetics of Yeast Alcohol Dehydrogenase for the oxidation reactons of n-alkanols in reverse micellar'water/Aerosol OT/organic solvent'system were investigated.It was indicated that the more hydrophobic the organic solvent was,the higher activity the expresses,with isooctane being the best among various solvents examined.The optimum temperature for the enzyme in reverse micelles is around 25℃and the activation energy determined is about 52kJ/mol,which is a little lower than that reported in aqueous system.Activity of the enzyme in reverse micelles rises with the increase of water content R (H_2 O]/[AOT])until it reaches about 50 where phase transilation will occur.The high concentrations of substrate,far exceeding the Michaelis constant,cause the reaction rates to increase monotonically with the increase of pH, whereas small concentrations lower than give a maximum rate around pH 8.2.It was found that the substrate specificity of alcohol dehydrogenase in reverse micellar system was quite different from that in aqueous system and the apparent Km value for n-butanol,the most suitable substrate of the enzyme in reverse micelles,was 3.30mmol/L,which is smaller than that determined in bulk water,4.34mmol/L.
出处
《华东理工大学学报（自然科学版）》
CAS
CSCD
1996年第3期336-341,共6页
Journal of East China University of Science and Technology
基金
国家自然科学基金
关键词
逆胶束
醇脱氢酶
有机溶剂
催化性能
增溶
reverse micelles
alcohol dehydrogenase
n-alkanols
oxidation reaction
organic solvents
