Hydrolysis and esterification of acylglycerols and analogs in aqueous medium catalyzed by microbial lipases

Abstract

The stereoselectivity of microbial lipases from Chromobacterium viscosum (CVL) and Rhizopus arrhizus (RAL) towards monoacylglycerols (rac-1(3)-oleoylglycerol and 2-oleoylglycerol), diacylglycerols (1,3-dioleoylglycerol and rac-1,2(2,3)-dioleoylglycerol) and 2-O-ether analogs (rac-1(3)-oleoyl-2-O-hexadecylglycerol and rac-1(3)-octanoyl-2-O-hexadecylglycerol) was determined. The results of the hydrolysis of 2-O-ether analogs confirmed the importance of the substituent at C-2 of acylglycerols in the stereoselective recognition by microbial lipases and also showed that acylation of mono- and diradylglycerols with oleic acid overlaps the hydrolysis reaction in aqueous medium. With the short-chain, water-soluble octanoic acid no significant esterification occurred. Using rac-1,2(2,3)-dioleoylglycerol as a substrate for the hydrolysis with RAL and CVL, the appearance of 1,3-dioleoylglycerol and of 1(3)-monooleoylglycerol was demonstrated. The possibility of chemical vs. enzyme-catalyzed isomerization of 1,2-dioleoylglycerol and of 2-oleoylglycerol is discussed.