固定化脂肪酶催化聚乙二醇脂肪酸酯的合成

Synthesis of Polyethylene Glycol Fatty Acid Esters by Immobilized Lipase

固定化假丝酵母（Ｃａｎｄｉｄａｓｐ．）－１６１９脂肪酶催化脂肪酸和不同聚合度的乙二醇形成酯。其中以聚乙二醇４００（ＰＥＧ４００）的酯化率较高，Ｃ１０－Ｃ１８的饱和脂肪酸与ＰＥＧ４００反应的酯化率相仿。反应体系中，月桂酸与ＰＥＧ４００的摩尔比大于２∶１时有利于酯化反应，作用的最适温度为４０℃，最适ｐＨ为６０。在比较的３０种添加有机溶剂中，饱和烷烃，芳香烃能促进反应，使酯化率提高２０％左右。反应开始添加５μｌ水有利于酶的作用，外加水量超过适量时，随外加水量的增加酯化率下降。在由２５ｍｍｏｌ月桂酸，１２５ｍｍｏｌＰＥＧ４００，１０ｍｇ固定化脂肪酶（１００ｕ），５ｍｌ己烷，５μｌ水组成的反应体系中，４０℃振荡反应２２ｈ，酯化率达４９８％。经薄层色谱，气相色谱鉴定，产物为聚乙二醇４００月桂酸酯。

Immobilized lipase from Candida sp.1619 on trueran was used to catalyze fatty acids and polyethylene glycols(PEGs) to form the corresponding esters.Among them,the highest esterification rate was obtained with PEG400 as alcohol.The nearly same esterification rates were obtained when fatty acids with carbon chain length from C 10 ～C 18 reacted with PEG400.The esterification of lauric acid with PEG400 at a molar ratio of more than 2∶1 showed good results.The optimal reaction temperature and pH was 40℃ and 6.0,respectively.Among the added solvents,hydrocarbons and aromatic hydrocarbons increased the esterification rate up to 20%.It was in favor to start the reactions by adding 5μl of water,but the esterification rates decreased with increasing the amount of added water.In the reaction system that composed of 2.5mmol lauric acid,1.25mmol PEG400 ,100units immobilized lipase(10mg),5ml hexane and 5μl water,shaken at 40℃ for 22 h,the esterification rate reached 49.8%.The esterified product was identified as PEG400 laurate by means of TLC and GC.