Effect of Surfactants on Pregastric Enzyme-Catalyzed Hydrolysis of Triacylglycerols and Esters

摘要

A brief overview is provided of the function of lipases and their structural features and of their mechanism of action and uses. Specifically, details of these properties are given for pregastric lipases. Data are then presented for the reactivity of kid pregastric lipase against 4-nitrophenyl butyrate in the presence of the surfactants Triton X-100, Tween 20, sodium taurocholate, cetyltrimethylammonium bromide, sodium dodecyl sulfate, Aerosol-OT, and lecithin, all rates of hydrolysis being measured at pH 6.5, 25 °C, and for the kid pregastric lipase-catalyzed hydrolysis of tributyrin in the presence of lecithin, sodium taurocholate, casein, and Tween 20 at pH 6.5, 35 °C. A combination kinetic model has been used to explain the dual characteristics of the kinetic behavior of the lipase. The added surfactant serves both as a solubilizer, increasing the concentration of the soluble form of the substrate, and as an emulsifier, which creates mixed lipid-micelles in solution. The enzyme behaves as both a lipase and an esterase, and the catalyzed hydrolysis of both the free substrate and the aggregates takes place simultaneously, with the rate of reaction being largely dependent on the concentration of added surfactant.