ADSORPTION AND ACTIVATION OF PANCREATIC LIPASE AT INTERFACES C. CHAPUS, M. SEMERIVA, M. CHARLES, AND P. DESNUELLE Centre de Biochimie et de Biologie Moleculaire 31, chemin Joseph Aiguier 13274 MARSEILLE CEDEX 2, FRANCE Pancreatic lipase is one of the digestive lipases converting dietary triglycerides into more polar monoglycerides and free fatty acids. This additional polarity appears to be necessary for the molecules to cross the membrane of the intestinal brush border membrane. Pancreatic liDase and probably other lipases as well, constitute an especially interesting case in Enzymology since they induce the very fast hydrolysis of water-insoluble substrates by a typical heterogeneous catalysis. The purpose of this paper is to discuss two important properties of pancreatic lipase, interfacial adsorption and interfacial activation. INTERFACIAL ADSORPTION IN THE ABSENCE OF BILE SALTS Although lipase is significantly active on molecularly disDersed substrate moleeules and micelles, its normal site of action is the oil-water interface of emulsified particles (1). Fig. 1 shows that, when more emulsion is attacked by a constant amount of enzyme, the activity increase runs parallel with that of adsorption. Moreover, Lineweaver-Burk representations obtained with emulsified substrate particles of different size indicate that the lipase-catalyzed reaction is not controlled, as in the usual case, by the substrate weight or molar concentration, but by the area of the interface (1). Fig. 2 gives another proof of lipase adsorption, the interface being provided here by highly hydrophobie siliconized 57

S. Gatt et al. (eds.), Enzymes of Lipid Metabolism © Plenum Press, New York 1978

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Adsorption and activation of pancreatic lipase at interfaces.

ADSORPTION AND ACTIVATION OF PANCREATIC LIPASE AT INTERFACES C. CHAPUS, M. SEMERIVA, M. CHARLES, AND P. DESNUELLE Centre de Biochimie et de Biologie M...
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