KINETIC-BEHAVIOR OF PANCREATIC LIPASE IN 5 SPECIES USING EMULSIONS AND MONOMOLECULAR FILMS OF SYNTHETIC GLYCERIDES

In the absence of colipase and bile salts, using tributyrin emulsions or monomolecular films of dicaprin at low surface pressure, we observe d that no significant lipase activity can be measured with Human Pancr eatic Lipase (HuPL), Horse Pancreatic Lipase (HoPL) or Dog Pancreatic Lipase (DPL). Only Porcine Pancreatic Lipase (PPL) and recombinant Gui nea Pig Pancreatic Lipase Related Protein of type 2 (r-GPL) hydrolyse pure tributyrin in the absence of any additive, as well as dicaprin fi lms at low surface pressures. The former lipases may lack enzyme activ ity because of irreversible interfacial denaturation due to the high e nergy existing at the tributyrin/water interface and at the dicaprin f ilm surface at low surface pressures. The enzyme denaturation cannot b e reflected in the number of disulfide bridges, since all the pancreat ic lipases tested here contain six disulfide bridges, but behaved Very differently at interfaces. We propose to use the surface pressure thr eshold, as determined using the monomolecular technique, as a criterio n for classifying lipases in terms of their sensitivity to interfacial denaturation.