7-hydroxycoumarinyl-arachidonate (7-HCA), a fluorogenic substrate for monoacylglycerol lipase (MAGL), can be used with MAGL as a novel fluorescence-based assay to screen small molecule inhibitors of MAGL.
MAGL protein catalyzed the hydrolysis of 7-HCA to generate arachidonic acid and the highly fluorescent 7-hydroxyl coumarin (7-HC). 7-hydroxycoumarin (7-HC) can be monitored spectrophotometrically (excitation at 335 nm, emission at 450 nm). Release of 7-HC was measured using a fluorometer. MAGL protein catalyzed the hydrolysis of 7-HCA with an apparent Km of 9.8 μM and Vmax of 1.7 mmol/min/mg of protein. The assay is specific for MAGL as assay buffer alone or heat-denatured MAGL protein showed no significant activity against 7-HCA [1]. 7-hydroxycoumarinyl Arachidonate is the arachidonic acid ester of 7-hydroxycoumarin (umbelliferone) and can be used as a substrate for cPLA2. Hydrolysis of 7-hydroxycoumarinyl arachidonate by phospholipase resulted in the release of the fluorescent compound [2,3].
References:
[1]. Wang Y, Chanda P, Jones P G, et al. A fluorescence-based assay for monoacylglycerol lipase compatible with inhibitor screening[J]. Assay and drug development technologies, 2008, 6(3): 387-393.
[2]. Huang Z, Laliberte F, Tremblay N M, et al. A continuous fluorescence-based assay for the human high-molecular-weight cytosolic phospholipase A2[J]. Analytical biochemistry, 1994, 222(1): 110-115.
[3]. Pickard R T, Chiou X G, Strifler B A, et al. Identification of essential residues for the catalytic function of 85-kDa cytosolic phospholipase A2 Probing the role of histidine, aspartic acid, cysteine, and arginine[J]. Journal of Biological Chemistry, 1996, 271(32): 19225-19231.