摘要：
为提高脂肪酶催化合成L-抗坏血酸棕榈酸酯的效果,以亲水性大分子羧甲基纤维素(CMC)的稀溶液溶解酶,通过物理吸附,将脂肪酶Pseudomonas cepacia lipase (PCL)和Aspergillus niger lipase (ANL)固定在反应器的内壁上,制备出固定化酶CMC-PCL和CMC-ANL,并用于催化L-抗坏血酸与棕榈酸的酯化反应,且与商品固定化酶Nov435比较.结果表明,相对于酶粉,两种固定化酶的活性和稳定性都有明显提高,尤其是CMC-PCL.催化反应24h,CMC-PCL使酯化反应的转化率达到63.7％.尽管3次重复使用后,CMC-PCL的催化活性有所降低,但可以通过加水和再固定化而使其催化活性恢复.再有,在反应体系中额外加入CMC,依赖CMC的强吸水性,可拉动反应平衡向酯合成方向移动,使CMC-PCL催化反应的转化率进一步提高到85.3％,可与Nov435的催化作用相媲美.同样条件下,加入CMC吸水,使Nov435催化的酯化反应的转化率达到89.6％.%To improve catalysis of lipases in synthesis of L-ascorbyl palmitate,Pseudomonas cepacia lipase and Aspergillus niger lipase were dissolved in dilute solution of hydrophilic macromolecular carboxy methyl cellulose (CMC) and immobilized on the inner wall of reactor by physical absorption to prepare immobilized lipases CMC-PCL and CMC-ANL.Then the immobilized lipases CMC-PCL and CMC-ANL were used in esterification of L-ascorbic acid and palmitic acid,and were compared with the commercial immobilized lipase Nov435 in terms of catalysis.It was found that two immobilized lipases behaved obvious increase in catalytic activity and stability relative to native enzyme powder,especially CMC-PCL.After 24 hours of catalytic esterification,CMC-PCL caused the reaction conversion rate achieved 63.7％.Although CMC-PCL showed decrease in catalytic activity after three times of recycling use in esterification,the activity could be restored by adding little water and then repeating immobilization.Furthermore,additional addition of CMC in reaction system caused the reaction conversion rate further increased to 85.3％ relies on strong water absorption of CMC,pulling reaction equilibrium to esterification,which could equal the catalytic role of Nov435.Under the same reaction condition,the water absorption brought the conversion rate of Nov435-catalyzed esterification to 89.6％.
