Shankar Sini, Agarwal Madhu, Chaurasia S P
Indian J Biochem Biophys. 2013 Dec;50(6):570-6.
Esterification of lauric acid with n-butanol, catalyzed by immobilized Candida antarctica lipase (CAL) in aqueous-organic biphasic solvent system was studied. Effects of various reaction parameters on esterification were investigated, such as type and amount of solvent, amount of buffer, pH, temperature, speed of agitation, amount of enzyme, butanol and lauric acid. The most suitable reaction conditions for esterification were observed at 50 degrees C and pH 7.0 using 5000 micromoles of lauric acid, 7000 pmoles of butanol, 0.25 ml phosphate buffer, 1 ml of isooctane as the solvent and 50 mg of immobilized enzyme in the reaction medium at agitation speed of 150 rpm. Maximum esterification of 96.36% was acheived in 600 min of reaction time at n-butanol to lauric acid molar ratio of 1: 0.7. Kinetic study for the esterification of lauric acid with n-butanol using immobilized CAL was carried out and the kinetic constants were estimated by using non-linear regression method. The estimated value of Michaelis kinetic constants for butanol (KmBt) and acid (KmAc) were 451.56 (M) and 4.7 x 10(-7)(M), respectively and the value of dissociation constant (KBt) of the butanol-lipase complex was 9.41 x 10(7)(M). The estimated constants agreed fairly well with literature data.
研究了在水-有机双相溶剂体系中，固定化南极假丝酵母脂肪酶（CAL）催化月桂酸与正丁醇的酯化反应。考察了各种反应参数对酯化反应的影响，如溶剂的类型和用量、缓冲液用量、pH值、温度、搅拌速度、酶量、正丁醇和月桂酸的用量。在50℃和pH 7.0的条件下，使用5000微摩尔月桂酸、7000皮摩尔正丁醇、0.25毫升磷酸盐缓冲液、1毫升异辛烷作为溶剂以及50毫克固定化酶，在150转/分钟的搅拌速度下，反应介质中观察到酯化反应的最适宜条件。在正丁醇与月桂酸摩尔比为1:0.7的情况下，反应600分钟，酯化率最高可达96.36%。对使用固定化CAL催化月桂酸与正丁醇酯化反应进行了动力学研究，并采用非线性回归方法估算了动力学常数。正丁醇（KmBt）和酸（KmAc）的米氏动力学常数估算值分别为451.56（M）和4.7×10⁻⁷（M），正丁醇-脂肪酶复合物的解离常数（KBt）值为9.41×10⁷（M）。估算常数与文献数据相当吻合。
