选择性修饰MCM-41固定化脂肪酶及其催化合成甾醇酯的应用

Selective Modification of MCM-41 Immobilized Lipase and Its Application in Sterol Ester Synthesis

将南极假丝酵母脂肪酶B(Candida antarctica lipase B,CALB)与三亚油酸甘油三酯进行分子对接,得到CALB的活性中心组成,其氨基酸残基中游离ε-NH2分布在远离活性中心的位置上,—COOH有小部分分布在活性中心.针对CALB活性基团的分布特点将MCM-41修饰成具有醛基的G-MCM-41及具有氨基的NH2-MCM-41.当G-MCM-41与CALB固定时,醛基与ε-NH2结合,酶负载量为87.4 mg/g,活性为1176 U/g,活性较高,当NH2-MCM-41与CALB固定时,氨基与—COOH结合,酶负载量为89.6 mg/g,活性为672 U/g,活性相对较低,结果证明了CALB分子氨基酸残基分布的结论.以一级大豆油和植物甾醇为底物,固定化脂肪酶催化酯交换反应,经响应面试验优化后酯交换率达到87.4%.

Candida antarctica lipase B (CALB) was docked with trilinolein to obtain the active site composition of CALB. The free ε-NH2 residues of CALB were located far from the active site and a small part of –COOH was located at the active site. Given the distribution characteristics of the CALB reactive groups, MCM-41 was modified into G-MCM-41 having aldehyde groups or NH2-MCM-41 having amino groups. CALB was immobilized with G-MCM-41 by binding the aldehyde group to ε-NH2 with a loading capacity of 87.4 mg/g, and the activity of the immobilized enzyme was as high as 1 176 U/g. CALB was immobilized with NH2-MCM-41 by binding the amino group to –COOH with a loading capacity of 89.6 mg/g, and the activity the immobilized enzyme was only 672 U/g. The results confirmed the distribution of amino acid residues in the CALB molecule. Using first-grade soybean oil and phytosterol as substrates, the transesterification rate of the immobilized lipase was 87.4% under the optimum conditions established using response surface methodology.