Abstract
AbstractFor green synthesis in organic phases, the catalysis of lipases needs to be further improved. Here a strategy is to simulate the activation of lipases at water/oil interface by immobilizing lipase on an available carrier material, which can replace the water at the interface to stabilize enzyme against denaturation from organic phase. The carrier is selected as cotton fiber on whichPseudomonas cepacialipase is immobilized by physical adsorption in a column glass bottle to form a simple bioreactor together with the bottle. In synthesis of fragrance ester hexyl acetate via transesterification of hexanol with vinyl acetate, the bioreactor exhibits a 3-fold increase in the ability to transform substrate, relative to native lipase in terms of the initial period of reaction at 37°C and 160 rpm. And also the bioreactor is very stable in catalysis for that it has an extra long half lifet1/2= 636 h, calculated from the decrease degree of molar conversions in six times of 6-hour transesterifications. More interestingly, the bioreactor behaves excellent activity at room temperature and in a static state, and can transform nearly 100% hexanol after 48 h. All these indicate that the bioreactor has great potential for industrial application.
Highlights
If the immobilization of enzymes can create an environment, as the reaction system in which synthesis can effectively proceed at room temperature [19], or even an environment, which makes it possible to avoid excessively considering the effect of temperature and shaking condition on enzymatic reaction, the immobilized lipases will be exceptionally favored in green synthesis for that energy consumption may be almost neglected in a sense
If there is a solid material that can replace water and does not participate in the enzymatic reaction, it can be employed as desired carrier to prepare immobilized lipases to effectively catalyze the transesterification for synthesis of ester compounds in organic phases
Cotton fiber seems to be a desired carrier for enzyme immobilization because the material is consisted of fluffy fibers in which there are a large hydroxyl groups, like water, naturally having ability to stabilize enzyme protein
Summary
W. Cao et al.: A simple room temperature-static bioreactor for effective synthesis of hexyl acetate 49 and decrease diffusion restriction of enzymes as far as possible, and the theoretical basis is the interfacial activation of lipases at the water/oil (organic phase) interface [9,10,11]. Substrates are allowed to access the active site and the excellent interfacial activity of lipases is observed at the water/oil interface [16]. This inspired researchers with great interests in simulation of the interfacial activation by immobilizing lipases on carriers [17], encapsulating them in gel [5] and cross-linking enzyme molecules [18], etc. If the immobilization of enzymes can create an environment, as the reaction system in which synthesis can effectively proceed at room temperature [19], or even an environment, which makes it possible to avoid excessively considering the effect of temperature and shaking condition on enzymatic reaction, the immobilized lipases will be exceptionally favored in green synthesis for that energy consumption may be almost neglected in a sense
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