COMPETITIVE-INHIBITION OF LIPOLYTIC ENZYMES .11. ESTIMATION OF THE INTERFACIAL DISSOCIATION-CONSTANTS OF PORCINE PANCREATIC PHOSPHOLIPASE A(2) FOR SUBSTRATE AND INHIBITOR IN THE ABSENCE OF DETERGENTS

Based on the strong inhibitory properties of (R)-2-decanoylamino-octan ol-1-phosphocholine and its phosphoglycol analogue for porcine pancrea tic phospholipase A(2), the corresponding 2-decanoyloxy derivatives ha ve been synthesised in both enantiomeric forms and their substrate pro perties for the enzyme were analysed. The high aqueous solubility in t he absence of detergents, combined with low critical micelle concentra tions of both the amide- and ester phospholipids allowed the estimatio n of the interfacial dissociation constants of the enzyme-substrate an d enzyme-inhibitor complexes by kinetic and direct binding techniques.