Adsorption and activation of pancreatic lipase at interfaces.

The first step of the lipase-catalyzed hydrolysis of insoluble long chain triglycerides is the adsorption of the enzyme to the interface. This adsorption, which is spontaneous when the interface is hydrophobic, is hindered by bile salts. Under these conditions, a small protein cofactor designated colipase adsorbs first and then anchors lipase at the interface. Interfacial adsorption enhances lipase activity, due, at least in part, to an acceleration of the rate-limiting deacylation step of the reaction. In this respect, lipase appears to be a most interesting model of an enzyme being activated by the presence of a lipid. The 3 steps of the heterogeneous catalysis induced by lipase, interfacial adsorption, interfacial activation and catalysis proper are under the control, respectively, of a serine hydroxyl group, a carboxyl and a histidine imidazole.