| Assay Method Information | |
| | Kat6B Assay 1 |
| Description: | A. Compound preparation 1. Prepare 10 mM stock solutions in 100% DMSO from solid material 2. Serial dilute 10 mM, 1 mM or 0.1 mM compound stocks 3-fold in 100% DMSO for 11-point dose responseB. Reagent preparation 1. Prepare 1× assay buffer containing 10 mM Tris HCL pH 8.0, 2.5 mM NaCl, 0.5 mM EDTA, 0.005% BSG and 0.02% Tween-20 2. Dilute Histone peptide (CPC Scientific) and AcCoA (Sigma) together in assay buffer to 2×. 3. Dilute KAT enzyme in assay buffer to 2×.C. Enzyme reaction 1. Final reaction conditions for each KAT assay in a 20 ul assay reaction volume: KAT6B 25 nM, 1 uM AcCoA, 2 uM H3 1-21 peptide, 60-minute reaction 2. Add 0.5 ul of diluted compound to the assay plate (384-well V-bottom polypropylene plates) or 0.5 ul of DMSO for control wells. 3. Add 10 ul of 2× Histone peptide/2×AcCoA mix to the assay plate. 4. Add 10 ul of 2× enzyme to the assay plate. 5. Stop the reaction after the indicated time with the addition of 2 ul of 5% formic acid 6. Each reaction was analyzed using self-assembled monolayer desorption/ionization time-of-flight mass spectrometry (Mrksich, Milan (2008) Mass Spectrometry of Self-Assembled Monolayers: A New Tool for Molecular Surface Science ACS Nano 2008 2 (1), 7-18; SAMDI Tech, Inc. (Chicago, Ill.)). 7. Area under the curve (AUC) for both substrate and product peaks was determined for KAT5 at M.W. 2561 [Substrate+H]+ and 2603 [Product+H]+ with a +/−1 Da tolerance, respectively 8. Area under the curve (AUC) for both substrate and product peaks was determined for KAT6a, KAT6B, KAT7 and KAT8 at M.W. 2723 [Substrate+H]+ and 2765 [Product+H]+ with a +/−1 Da tolerance, respectively. 9. Percent conversion to product was calculated by: AUCProduct/(AUCsubstrate+AUCProduct).D. Data analysis 1. IC50 values were determined by fitting the % conversion at each inhibitor concentration to the 4-parameter IC50 equation using Pfizer proprietary curve fitting software. 2. Ki values were determined by fitting the % conversion at each inhibitor concentration to the Morrison equation for tightbinding competitive inhibitors using Pfizer proprietary curve fitting software. |
| Affinity data for this assay | |
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