Abstract

Lipases (triacylglycerol acyl hydrolass EC 3.1.1.3) are defined as enzymes that catalyse the hydrolysis of triacylglycerols, releasing long-chain fatty acids. Germinating oilseeds have been explored as a possible source of lipases for biotechnological processing of oils and fats. However, purification and sensitive assays to detect a true lipase activity in plant cellular homogenates and culture media are required. The main aim of this study was to design a convenient, specific, sensitive and continuous lipase activity assay using natural long-chain triacylglycerols (TAGs). Oil was ex tracted from Parinari glaberrimum seed kernels and the pu rified TAGs were used as a substrate for detecting low levels of lipase activities. An increase in the fluorescence was observed, which is due to the parinaric acid released by various lipase activities. This increase in the fluorescence intensity is linear with time and proportional to the amount of lipase added. This new method, performed under non-oxidative conditions, was applied successfully to detect low lipase levels in crude protein extracts from plant seeds.

Key words: Brassica napus, fluorescent lipids, lipase assay, plant lipases.