NEW FLUOROGENIC TRIACYLGLYCEROL ANALOGS AS SUBSTRATES FOR THE DETERMINATION AND CHIRAL DISCRIMINATION OF LIPASE ACTIVITIES

A new type of fluorogenic and isomerically pure 1(3)-O-alkyl-2,3 (3,2) -diacyl glycerols was synthesized that can be used as substrate for th e determination of lipase activities. These compounds contain a fluore scent pyrene acyl chain and, as a potent quencher of pyrene fluorescen ce, a trinitrophenylamino acyl residue. In their intact form, the fluo rogens show only low fluorescence intensity. Upon lipase-induced or ch emical hydrolysis of the substrates, however, the fluorophore and quen cher separate from each other. This leads to a gradual increase in pyr ene fluorescence, reflecting the time-dependent progress of lipolysis and, under substrate saturation conditions, lipase activity. This lipa se assay is continuous and does not require separation of substrate an d reaction products. Short- and long-chain homologues as well as optic al isomers of the fluorogenic alkyldiacyl glycerols were hydrolyzed by pancreatic lipase, hepatic lipase, and lipoprotein lipase at highly d ifferent rates depending on the substrate or enzyme preparation and so urce (e.g., postheparin plasma or cultured cells). It is proposed that a useful set of enantiomeric and/or homologous substrates in combinat ion with appropriate reaction media might be applied to the selective determination of a lipase in a mixture of lipases, e.g., hepatic and l ipoprotein lipase in PHP, for medical diagnostics.-Duque, M., M. Graup ner, H. Stutz, I. Wicher, R. Zechner, F. Paltauf, and A. Hermetter. Ne w fluorogenic triacylglycerol analogs as substrates for the determinat ion and chiral discrimination of lipase activities.