| Assay Method Information | |
| | In Vitro Histone Deacetylase Assay II |
| Description: | The measurement of HD AC 11 deacetylase activity was performed using an electrophoretic mobility shift assay by Nanosyn (Santa Clara, Calif.). Full length human recombinant HD AC 11 protein was expressed in baculoviral system and purified by affinity chromatography. The enzymatic reactions were assembled in 384 well plates in a total volume of 25 μL in a reaction buffer composing: 100 mM HEPES, pH 7.5, 25 mM KCl, 0.1% bovine serum albumin, 0.01% Triton X-100, 1% DMSO (from compounds), 2 μM of the fluorescently labeled peptide substrate and enzyme. The enzyme was added at a final concentration of 10 nM. The peptide substrate FAM-RHKK(tri-fluor-Ac) NH2 was used. The compounds were tested at 12 concentrations spaced by 3× dilution intervals. Negative control samples (0%-inhibition in the absence of inhibitor) and positive control samples (100%-inhibition) were assembled in replicates of four in each assay plate. The reactions were incubated at 25° C. and quenched by the addition of 45 μL of termination buffer (100 mM HEPES, pH 7.5, 0.01% Triton X-100, 0.05% SDS).The terminated assay plates were analyzed on LabChip 3000 microfluidic electrophoresis instrument (Perkin Elmer/Caliper Life Sciences). The fluorescence intensity of the electrophoretically separated de-acetylated product and substrate peptide was measured. Activity in each sample was determined as the product to sum ratio (PSR): P/(S+P), where P is the peak height of the product peptide and S is the peak height of the substrate peptide. Percent inhibition (Pinh) is determined using the following equation:P inh=(PSR0%−PSRinh)/(PSR0%−PSR100%)*100,where PSRinh, is the product sum ratio in the presence of inhibitor, PSR0% is the average product sum ration in the absence of inhibitor and PSR100% is the average product sum ratio in 100%-inhibition control samples. The IC50 values of inhibitors were determined by fitting the percent inhibition curves with 4 parameter dose-response model using XLfit 4 software. |
| Affinity data for this assay | |
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