表面活性剂改性膨润土固定化脂肪酶的初步研究

The preliminary study on modification of bentonite with surfactant for Candida rugosa lipase immobilization

表面活性剂改性载体影响酶的催化活性,为此,考察了复合表面活性剂改性膨润土对固定化酶特性的影响,以阳—阳离子表面活性剂、阳—阴离子表面活性剂、阳—非离子表面活性剂分别对钠基膨润土(Na-Bent)进行改性,通过吸附法对褶皱假丝酵母脂肪酶(Candida rugosa lipase,CRL)进行固定化,制备复合表面活性剂改性膨润土固定化酶。以橄榄油水解反应表征酶活性,对比不同的复合离子表面活性剂改性膨润土固定化CRL酶的结果发现,由十六烷基三甲基溴化铵(CTAB)和曲拉通100(TX100)复合离子表面活性剂改性膨润土制备的固定化酶(CTAB/TX100-Bent-CRL)的比活回收率可达到292. 8%,相较于游离酶CRL,其催化活性得到改善。催化特性研究表明:CTAB/TX100-Bent-CRL的最适反应温度和p H值分别为40℃和7. 0,与游离酶ORL相比,固定化酶的耐受性和储藏稳定性均得到改善,在温度为20℃～60℃、p H 5. 0～9. 0范围内均能发挥较好的催化性能。在温度为60℃的反应条件下,CTAB/TX100-Bent-CRL仍能保持最适温度条件下活力的89. 0%。在4℃下储藏15 d后,固定化酶仍能保持初始活力的59. 7%,而Na-Bent-CRL和游离酶CRL的残留活力分别为45. 7%和33. 3%。

Modification of supports with surfactant affect the catalytic activity of the enzyme,hence,in this paper,the effects of compound used for modification of bentonites on the immobilized lipase properties were investigated.Na-bentonite(Na-Bent)was modified using cation-cationic surfactant,cation-anionic surfactant and cation-nonionic surfactant,respectively,and the Candida rugosa lipase was immobilized on modified bentonite by adsorption.The activity of lipase was measured by hydrolysis of olive oil emulsion.Comparing the results of CRL enzyme immobilization on the bentonite modified by different composite ionic surfactants,it was found that the recovery of specific activity of CTAB/TX100-Bent-CRL,Candida rugosa lipase immobilized on the bentonite modified by cetyltrimethylammonium bromide(CTAB)and Triton X-100(TX100)cation-nonion surfactant could reach 292.8%,which was better than that of free CRL.The investigation of catalytic properties showed that the optimum reaction temperature and pH value of CTAB/TX100-Bent-CRL were 40℃and 7.0,respectively.The immobilized enzyme CTAB/TX100-Bent-CRL,has a wider pH and temperature range than free CRL.Better catalytic performance was exhibited at the temperature of 20℃~60℃and pH 5.0~9.0.At 60℃,CTAB/TX100-Bent-CRL was able to maintain 89.0%of its optimum activity.Stored at 4℃for 15 days,the residual activity of immobilized CRL was 59.7%,while the Na-Bent-CRL and free CRL can only retained 45.7%and 33.3%,respectively,of their initial activity.