Customizing lipases for biocatalysis: a survey of chemical, physical and molecular biological approaches

Lipases (triacylglycerol ester hydrolases, EC 3.1.1.3) are ubiquitous enzym es that catalyze the breakdown of fats and oils with subsequent release of free fatty acids, diacylglycerols, monoglycerols and glycerol. Besides this , they are also efficient in various reactions such as esterification, tran sesterification and aminolysis in organic solvents. Therefore, those enzyme s are nowadays extensively studied for their potential industrial applicati ons. Examples in the literature are numerous concerning their use in differ ent fields such as resolution of racemic mixtures, synthesis of new surfact ants and pharmaceuticals, oils and fats bioconversion and detergency applic ations. However, the drawbacks of the extensive use of lipases (and biocata lysts in general) compared to classical chemical catalysts can be found in the relatively low stability of enzyme in their native state as well as the ir prohibitive cost. Consequently, there is a great interest in methods try ing to develop competitive biocatalysts for industrial applications by impr ovement of their catalytic properties such as activity, stability (pH or te mperature range) or recycling capacity. Such improvement can be carried out by chemical, physical or genetical modifications of the native enzyme. The present review will survey the different procedures that have been develop ed to enhance the properties of lipases. It will first focus on the physica l modifications of the biocatalysts by adsorption on a carrier material, en trapment or microencapsulation. Chemical modifications and methods such as modification of amino acids residues, covalent coupling to a water-insolubl e material, or formation of cross-linked lipase matrix, will also be review ed. Finally, new and promising methods of lipases modifications by genetic engineering will be discussed. (C) 2000 Elsevier Science B.V. All rights re served.