Action of cutinase at the triolein-water interface. Characterisation of interfacial effects during lipid hydrolysis using the oil-drop tensiometer as a tool to study lipase kinetics

Interfacial events during lipid hydrolysis by cutinase are described as measured with the oil-drop tensiometer. A linear relation between enzyme concentration and initial decrease of oil-water interface tension (gamma(O/W)) due to lipolytic activity was observed. The amount of hydrolysis products showed a non-linear relation with gamma(O/W) Hydrolysis is linear with time, even when the area occupied by the fatty acid molecules exceeds the drop surface by a factor 7000. At pH 9.0, fatty acids were found to partition mainly in the oil phase. Formation of calcium soaps and ionization increase the impact of fatty acids on gamma(O/W) without affecting enzyme activity. The presence of fatty acids at the interface, added prior to cutinase, delayed hydrolysis effects on gamma(O/W). Fatty acids in the water phase almost completely abolished adsorption effects on gamma O/W when the concentration was over the critical micellar concentration (cmc). Copyright (C) 1996 Elsevier Science Ireland Ltd