| Assay Method Information | |
| | Inhibition Assay |
| Description: | In order to have an assay method more conducive to high-throughput screening than those published for measuring the NAE hydrolyzing activity of NAAA, we developed the fluorogenic PEA analog N-(4-methyl coumarin)palmitamide (PAMCA), which is hydrolyzed to fluorescent 7-amino-4-methyl coumarin (AMC) and palmitic acid. For three point concentration inhibition assays with hNAAA the following procedure is used. Purified activated NAAA (final concentration of 0.25 μg/mL) is incubated in assay buffer (100 mM citrate-phosphate buffer, pH 4.5, 3 mM DTT, 0.1% Triton X-100, 0.05% BSA, and 150 mM NaCl) made up to a total volume of 180 μL, followed by addition of the compound dissolved in 10 μL DMSO (along with DMSO neat for the control sample) with the final concentrations for each compound of 100, 10, and 1 μM, in triplicate on a 96 well plate. These samples are allowed to incubate for 15 min at room temperature and then 10 μL of a PAMCA stock solution in DMSO (final PAMCA concentration [5 μM]) was added. After 5 minutes of agitation on a shaking plate, the reaction is allowed to proceed at 37° C. for 120 minutes, with fluorescence readings taken every 10 minutes at a wavelength of 460 nm (using an excitation wavelength of 360 nm) on a Synergy HT Plate Reader using Gen5 software from Bio-Tek. The enzyme activity is calculated by converting the relative fluorescence units to AMC formed, using a standard curve of AMC. For compounds that inhibit hNAAA in range IC50 <1 μM full inhibition curves using eight different concentrations of inhibitor (8 point assay) are generated. The assay procedure used is the same as the three point assay. For ostensibly covalent compounds (as observed by a significant decrease in the slope of a plot of fluorescence vs. time in three point screen) samples are allowed to incubate for 2 hours at 37° C., instead of 15 minutes, before addition of 10 μL of a PAMCA stock solution in DMSO for a final PAMCA concentration of 5 μM. After 5 minutes of agitation on a shaking plate, the reaction is allowed to proceed at 37° C. for 120 minutes Inhibition constants are calculated using pro Fit software (Quantum Soft, Uetikon am See, Switzerland) and a Levenberg-Marquardt algorithm. |
| Affinity data for this assay | |
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