Hydrolysis of Mixed Monomolecular Filme of phosphatidulchoiline/Triacylglycerol by Pancereatic Phospholipase A2

Abstract

We studied the effect of glycerides on pancreatic phospholopase A₂ hydrolysis of mixed monomoecular films of trioctanoylglyderol/1, 2‐didodecanoyl‐sn‐ glycero‐3‐phosphocholine with the technique of Piéroni and Verger [(1979) J. Biol. Chem. 254, 10090–10094]. The quantity of enzyme adsorbed to the interface was concomitantly determined with [³H] amidinated phospholipase. At phospholipid packing above the critical penetration pressure, triacylglycerol stimulates phosphatidylcholone hydrolysis to a great extent. On th eother hans, the activity of pancreatic phospholipase A₂ on a mixed film is inhibited by the action o fpandreatic lipase. Interface binding of phospholipase A₂ to the lipid sustrate does not imply activity.