Resorufin butyrate as a soluble and monomeric high-throughput substrate for a triglyceride lipase

Triglyceride lipases such as lipoprotein lipase, endothelial lipase, and hepatic lipase play key roles in controlling the levels of plasma lipoprotein. Accordingly, small-molecule modulation of these species could alter patient lipid profiles with corresponding health effects. Screening of these enzymes for small-molecule therapeutics has historically involved the use of lipid-based particles to mimic native substrates. However, particle-based artifacts can complicate the discovery of therapeutic molecules. As a simplifying solution, the authors sought to develop an approach involving a soluble and monomeric lipase substrate. Using purified bovine lipoprotein lipase as a model system, they show that the hydrolysis of resorufin butyrate can be fluorescently monitored to give a robust assay (Z' > 0.8). Critically, using parallel approaches, they show that resorufin butyrate is soluble and monomeric under assay conditions. The presented assay should be useful as a simple and inexpensive primary or secondary screen for the discovery of therapeutic lipase modulators.