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Unusually versatile substrate specificity is shown by lipases. Not only do they hydrolyze triacylglycerols-for example, in the stomach and intestine during digestion of dietary fat-and various synthetic esters and amides, but their high stability in organic solvents permits their use in transesterification reactions and ester synthesis as well. Reactions based on lipase catalysis usually proceed with high regio- and enantioselectivity. Thus, the Ca antagonist diltiazem (1) was obtained with lipase from Serratia marcescens. Over 30 lipases have been cloned in the last few years. Since the tertiary structure of 12 lipases is known, there are presently significant efforts to improve this class of enzymes by protein engineering techniques, in view of their use in detergents and other fields of industrial application.

. The interfacial activation of Pseudomonas lipases involves conformational rearrangements of surface loops and appears to conform to models of activation deduced from the structures of fungal and mammalian lipases. Factors controlling the conformational rearrangement are not understood, but a comparison of crystallization conditions and observed conformation suggests that the conformation of the protein is determined by the solution conditions, perhaps by the dielectric constant.