溶胶-凝胶法固定化Candida sp．99-125脂肪酶

Immobilization of Lipase by Sol-Gel Entrapment

利用正硅酸甲酯(TMOS)和丙基三甲氧基硅烷(PTMS)为复合硅源,以PEG(M_W=20000)为稳定剂,以HCl为催化剂,经过溶胶-凝胶过程包埋假丝酵母99-125脂肪酶．研究得到最适的固定化条件为:PTMS与TMOS的摩尔比4∶1,R值(水与硅源的摩尔比)20,给酶量(酶占硅源的质量百分数)3．71％,PEG与酶的质量比(1～1．5)∶1,硅源水解时间35 min．在该条件下,固定化脂肪酶的最高酯化活力是游离酶最高酯化活力的2．02倍．固定化脂肪酶在100℃保温2 h后酶活仍维持为59．1％,固定化酶催化特定酯化反应,经过8批连续反应96 h后酶活维持不变．

Candida sp. 99-125 lipase was entrapped in organic-inorganic sol-gel powder prepared by polymerization of tetramethoxysilane （TMOS） and propyltrimethoxysilane （PTMS）. PEG （MW=20000） and HCl were used as stabilizing additive and catalyst during the sol-gel process, respectively. The optimal preparation conditions were studied, which are PTMS/TMOS molar ratio at 4：1, water/silane molar ratio 20, enzyme loading 3.71% （ω） of silane precursor and hydrolysis time of silane precursor for 35 min. The specific activity of immobilized lipase was 2.02 times higher than that of non-immobilized lipase under the optimal water content in esterification reaction system. The esterification activity of immobilized lipase retained 59. 1% of the initial activity after 2 h incubation under 100 ℃, and the activity of immobilized lipase remained almost unchanged after 8 consecutive batches of each 12 h reaction.