PREPARATION OF A LIPID-COATED LIPASE AND CATALYSIS OF GLYCERIDE ESTER SYNTHESES IN HOMOGENEOUS ORGANIC-SOLVENTS

A lipid-coated lipase was prepared by mixing aqueous solutions of lipase amd dialkyl amphiphiles: A hydrophilic surface of the enzyme is covered with a lipid layer, of which lipophilic two-long-alkyl tails solubilize the enzyme in hydrophilic organic solvents. The lipid-coated lipase was prepared in various conditions by changing hydrophilic head groups of lipid molecules, a ratio of lipid/lipase, and an origin of lipase; the complex prepared from nonionic amphiphiles and lipase D from Rhizopus delemar showed a high stability and a high enzymatic activity in hydrophobic organic solutions. The lipid-coated lipase catalyzed di- and triacylglycerol syntheses from monoacylglycerols and aliphatic acids in the homogenous and dry benzene solution in the presence of two pieces of molecular sieves (water: 80 ppm). The lipid-coated lipase could also catalyze ester exchange reactions in organic solvents with a small amount of water (250 ppm). Enzymatic activity was affected by a nature of organic solvents and a water content in organic solvents. The catalytic activity of the lipid-coated lipase was highly efficient compared with other enzyme systems such as the poly(ethylene glycol)-grafted lipase and the direct dispersion of lipase powder for glyceride syntheses in the dry organic solution.