Assay Method Information

Assay Name:  Enzymatic Assay
Description:  Endothelial lipase activity was measured using a fluorescent substrate, A10070, (Invitrogen, CA) doped into an artificial vesicle containing DMPG (Avanti Polar Lipids) as the excipient. Vesicles were prepared by combining 285 uL of 1 mMDMPG in a 1:1 mixture of MeOH and CHCl3 with 15 uL of 1 mM A10070 in a 1:1 mixture of MeOH and CHCl3. The mixture was dried under nitrogen and resuspended in 150 uL of 50 mM HEPES pH 8.0 buffer containing 100 mM NaCl and 0.2 mM EDTA. The sample was allowed to sit at rt for 15 min and then was sonicated 3x4 mins on ice with a Branson Sonicator using duty cycle 1. This preparation provides vesicles with a mole fraction of 0.05 for the FRET substrate.The enzymatic assay was measured using white, opaque 96-well half area plates. Each well contained 60 uL of assay buffer (50 mM HEPES pH 8.0, 50 mM NaCl and 1 mM CaCl2) and 2 ul of a DMSO solution containing compound of interest. Conditioned media obtained from HT-1080 cells, which were transformed by RAGE technology (Athersys) to overexpress endogenous EL, was added and the reaction was allowed to incubate for 20 min at 37deg; C. with gentle agitation. The reaction was started by the addition of 20 uL of a 1:4 dilution of vesicles. The final total reaction volume was 100 uL. The reaction rates were measured on a Gemini plate reader with an excitation wavelength of 488 nm and a emission of 530 nm. Readings were taken every 20 seconds for 10 min with agitation between each reading. The slope of the linear portion of the readout was used to calculate the rate of the reaction.
Affinity data for this assay
 

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