Hydrolysis of mixed monomolecular films of triglyceride/lecithin by pancreatic lipase.

The main purpose of this study was to describe the influence of lecithin upon lipolysis of mixed monomolecular films of trioctanoylglycerol/didodecanoylphosphatidycholine by pancreatic lipase in order to mimic some physiological situations. The quantity of enzyme adsorbed to the interface was simultaneously determined using 5-thio-2-nitro[14C]benzoyl lipase. Lipolytic activity was enhanced 3- to 4-fold in the presence of colipase, an effect which is attributed to increased enzyme turnover number. When a pure triglyceride film was progressively diluted with lecithin, the minimum specific activity of lipase exhibited a bell-shaped curve: a mixed film containing only 20% trioctanoylglycerol was hydrolyzed at the same rate as a monolayer of pure triglyceride.