亲水改性聚氨酯纳米纤维酶膜催化油水两相体系转糖苷反应

利用静电纺丝法制备含LiCl的聚氨酯(PU)纳米纤维，用牛血清白蛋白(BSA)对纤维亲水改性，于其上固定b-D-半乳糖苷酶，提高酶在油水两相介质中催化转糖苷反应的活力. 结果表明，以PU浓度26%(w)的电纺液制备的直径240~300 nm的PU纤维膜在LiCl辅助作用下吸附BSA高达222 mg/g，使纤维膜的水接触角由103.7o降至77.3o. 改性PU膜固定化酶比活力为1.59 U/mg，而未改性PU膜仅为其79.2%. 改性膜固定化酶55℃下的活力半衰期高达游离酶的14倍，在4℃下储存45 d活力仍保持80%，而游离酶活力仅剩余16.3%；改性膜固定化酶重复催化42次转糖苷反应活力仍能保持31%.

Transgalactosylation Reaction Catalyzed by Hydrophilic Modified PU Nanofibrous Enzyme Membrane in Oil-Water System

Polyurethane (PU) nanofiber with the diameter of 240~300 nm was prepared by electrospinning from 26%(w) PU solution containing LiCl. In order to increase the catalytic efficiency of b-D-galactosidase immobilized on PU nanofibrous membrane, suitable microenvironment on the membrane was pre-created by hydrophilic modification. BSA was adsorbed with LiCl on PU nanofibrous membrane at the high loading of 222 mg/g. The contact angle of modified PU nanofibrous membrane with water was thus reduced from 103.7o to 77.3o. Then b-D-galactosidase was immobilized on the modified membrane and catalyzed the transgalactosylation reaction in hexanol-water biphasic system. The specific activity of b-D-galactosidase immobilized on PU nanofiber membrane was 1.59 U/mg, while the activity of b-D-galactosidase adsorbed on unmodified PU nanofibrous membrane was its 79.2%. Compared with native enzyme, the half-life of b-D-galactosidase immobilized on PU nanofiber membrane incubated at 55℃ was increased 14 times. The storage stability of b-D-galactosidase immobilized on the membrane at 4℃ was also increased obviously, after storage for 45 d, the activity retained over 80%, whereas the activity of native b-D-galactosidase only 16.3%. The activity of b-D-galactosidase immobilized on PU nanofiber membrane was retained 31% after reuse in 42 times.