Determination of Lipase Activity in Organic Solvent Using Fluorescent Substrate and Its Application to the Screening of Lipase Inhibitor

Abstract

Measurement of the activity of a lipase-detergent complex in a homogeneous system using 4-methylumbelliferyl oleate as a fluorescent substrate was studied. A linear relation between the quantity of the complex and the amounts of 4-methylumbelliferone formed was obtained up to 240pmol/tube when incubated with 0.05mM 4-methylumbelliferyl oleate in aqueous 95% tetrahydrofuran. Under these conditions, the activity of the complex is about 1pmol min^-1 μg^-1. The maximum activity was obtained in neutral or weakly alkaline medium. In this assay system, metal ions such as Fe³⁺ and Co²⁺ strongly inhibited the activity. This method could be applied to the screening of lipase inhibitors in foods.