烷基咪唑离子液体对脂肪酶催化酯水解反应活性的影响

考察了1-烷基-3-甲基咪唑类离子液体对柱状假丝酵母脂肪酶(CRL)催化橄榄油水解反应活性的影响,利用电导法确定了磷酸盐缓冲液中Br^-,Cl^-,BF₄]^-系列咪唑离子液体的临界胶束浓度(CMC)和PF₆]^-系列咪唑离子液体的溶解度.结果显示,离子液体的阴、阳离子对酶活性的影响规律与离子液体的Kosmotropicity性质无明显关联,但与离子液体在体系中的含量密切相关,在最适离子液体含量时,酶活性达到最高;阳离子C_nMIM]⁺中的n越大,可促进酶活性的离子液体适宜含量越低;Br^-,BF₄]^-系列离子液体的浓度超过CMC时则抑制酶活;阴离子对酶活性的最大促进作用顺序为Br^->Cl^->BF₄]^->PF₆]^-.离子液体对酶活性的影响随体系pH和温度的不同而改变,在最适离子液体浓度时的最适pH均为7.000.在pH 7.000,30 ^oC以及C₈MIM]Br离子液体浓度为47.6 mmol/L的最佳条件下,最高相对酶活力和比活力分别达到1734%和54.4 U/mg protein.

Effect of imidazolium ionic liquids on the hydrolytic activity of lipase

The effect of 1-alkyl-3-methylimidazolium ionic liquids (ILs) on the hydrolysis activity of Candida rugosa lipase (CRL) toward triacylglycerol was investigated. The critical micelle concentrations (CMC) of ILs with Br^-, Cl^-, and BF₄]^- anions and the solubility of ILs with PF₆]^- anions were determined in phosphate buffer. Results suggested that the content of the ILs, not kosmotropicity, highly influenced the effects of anions and cations of ILs on CRL activity. As the length of alkyl chain of the cation C_nMIM]⁺ increased, lower IL content was required to achieve high enzyme activity. Once the concentrations of the ILs with Br^-, Cl^-, and BF₄]^- anions exceeded the CMC value, enzyme activity was suppressed. The positive promotion effect of anions on enzyme activity was in the order of Br^- > Cl^- > BF₄]^- > PF₆]^-. The effect of ionic liquid on enzyme activity was highly dependent on the pH and temperature of the system, with the optimum pH being 7.000. Under optimal conditions of pH 7.000, 30℃, and 47.6 mmol/L of C₈MIM]Br, the highest relative activity of CRL (1734%) was achieved, with a specific activity of 54.4 U/mg protein.