脱脂棉固定化脂肪酶PCL催化合成乙酸癸酯

Synthesis of decyl aceate catalyzed by cotton-immobilized lipase PCL

乙酸癸酯是一种广泛用于食品和医药品的芳香添加剂。因天然提取量少,不能满足需求,通常利用合成方法制备乙酸癸酯。由于化学法污染环境严重、产率低且杂质多,而非水相酶催化合成乙酸癸酯是一种绿色合成途径,而且副反应少、产率高、产物易于分离提纯。所以,选用假单胞菌脂肪酶(Pseudomonas cepacia lipase,PCL)为生物催化剂,在37℃和160 r/min的条件下,通过物理吸附,将PCL固定在脱脂棉上,制备脱脂棉固定化PCL,并用于催化正癸醇与乙酸乙烯酯反应,合成乙酸癸酯。结果发现,酶与棉的质量比为10∶12时,脱脂棉固定化PCL的活性最高,在37℃和160 r/min,催化反应6 h,转化率达95%以上。在同样条件下,PCL酶粉仅能催化29%的底物反应。如果重复利用这种固定化酶,每次催化6 h,第3次的转化率仍可达到92%。在25℃和静置条件下,6 h后,固定化酶依然能转化底物89%。可见,脱脂棉固定化酶PCL的催化活性明显提高,且具有低碳催化特性。

Decyl acetate is an aromatic additive widely used in food and medicine. Due to the lack of natural extraction amount, the demand cannot be met and thus usually prepared by synthesis methods. The chemical synthesis method has the problem of serious pollution, low yield with many impurities, however, on contrary, the enzymatic reaction in non-aqueous phases is a green synthesis method, and has advantages such as less side reaction, high yield, and the product is easy to separate and purify. Thus, Pseudomonas cepacia lipase （PCL）, as a biocatalyst, was immobilized on absorbent cotton by physical adsorption at 37 ~C and 160 r/min. The prepared cotton-immobilized PCL （cotton-PCL） was used in catalyzing reaction of decyl alcohol to vinyl acetate. The results showed that, cotton- PCL displayed better catalytic activity when the mass ratio of enzyme to cotton was 10 ： 12. After catalysis for 6 h at37℃and 160 r/min, the molar conversion of reaction reached to more than 95%. And at the same conditions, native PCL only transforms 29% of substrate. Repeating catalysis for three times and 6 h for each time at the above reaction conditions, the conversion ratio can still reach 92 % . Even under a static condition at 25℃, catalyzed cotton-PCL could also converse 89% substrate. It was obvious that cotton-PCL behaved a relatively high activity with low carbon catalytic property.