Immobilization and Chemical Modification

Lipases are not the perfect catalysts despite their interesting properties. They may exhibit sub-optimal activity and enantioselectivity and may be unstable. Their cost may decrease their attractiveness for industrial applications. The use of immobilized enzymes may solve some of these issues by enhancing stability and reuse and decreasing cost of the biocatalyst. 

Adsorption, hnkage, bonding of the enzyme to an insoluble support and entrapment of the enzyme in polymeric gels or encapsulation have all been used as ways to immobilise lipases [38]. To be successful, various parameters of the immobilization support need to be considered such as its mechanical strength, chemical and physical stability, its hydrophilicity/lipophilicity and the relevant loading capacity of the enzyme [39]. 

Pyromellitic dianhydride has been used to modify the amino groups of P. cepacia lipase which was then used in transesterification reactions in n-octane and DMF. The modified lipase gave initial reaction rates in DMF higher than unmodified pH-tuned lipase (that showed no activity at all under the same conditions) [32]. 

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