A Spectrophotometric Lipase Activity Assay by Coupled Lipase-Lipoxygenase in Reverse Micelles

Abstract
A new, continuous spectrophotometric method is described for determining lipase activity using a reverse micelle system, in which lipase (EC 3.1.1.3) and lipoxygenase (EC 1.13.11.12) are dissolved. The reverse micelle system consists of 2-ethyl hexyl sodium sulfosuccinate (AOT)-isooctane and water. Trilinolein is used as the lipase substrate; linoleate hydroperoxide is the end product of the oxidation catalyzed by lipoxygenase, which acts as an auxiliary coupled-enzyme of lipase. The method appears useful both for detailed kinetic studies of lipase and for serial analyses using sunflower oil, a cheaper substrate. This assay offers the typical advantages of the continuous direct photometric methods in that it is rapid, reproducible and sufficiently sensitive for measuring lipase activity even in some crude commercial preparations.