Assay Method Information

Assay Name:  In Vitro DGAT2 Assay
Description:  For determination of IC50 values, the reactions were carried out in 384-well white Polyplates (Perkin Elmer) in a total volume of 20 μL. To 14 of compounds dissolved in 100% DMSO and spotted at the bottom of each well, 5 μL of 0.04% bovine serum albumin (BSA) (fatty acid free, Sigma Aldrich) was added and the mixture was incubated at room temperature for 20 minutes. To this mixture, 10 μL of hDGAT2 membrane fraction (0.01 mg/mL) diluted in 100 mM Hepes-NaOH, pH 7.4, 20 mM MgCl2 containing 200 nM methyl arachidonyl fluorophosphonate (Cayman Chemical; dried from ethyl acetate stock solution under argon gas and dissolved in DMSO as 5 mM stock) was added. After this mixture was preincubated at room temperature for 2 hours, DGAT2 reactions were initiated by the addition of 4 μL of substrates containing 30 μM [1-14C]decanoyl-CoA (custom-synthesized by Perkin Elmer, 50 mCi/mmol) and 125 μM 1,2-didecanoyl-sn-glycerol (Avanti Polar Lipids) dissolved in 12.5% acetone. The reaction mixtures were incubated at room temperature for 40 min and the reactions were stopped by addition of 5 μL of 1% H3PO4. After the addition of 45 μL MicroScint-E (Perkin-Elmer), plates were sealed with Top Seal-A covers (Perkin-Elmer) and phase partitioning of substrates and products was achieved using a HT-91100 microplate orbital shaker (Big Bear Automation, Santa Clara, Calif.). Plates were centrifuged at 2,000×g for 1 min in an Allegra 6R Centrifuge (Beckman Coulter) and then were sealed again with fresh covers before reading in a 1450 Microbeta Wallac Trilux Scintillation Counter (Perkin Elmer). DGAT2 activity was measured by quantifying the generated product [14C]tridecanoylglycerol in the upper organic phase. Background activity obtained using 50 μM of (1R, 2R)-2-({3′-Fluoro-4′-[(6-fluoro-1, 3-benzothiazol-2-yl)amino]-1,1′-biphenyl-4-yl}carbonyl)cyclopentanecarboxylic acid (US 20040224997, Example 26) or (R)-1-(2-((S)-1-(4-Chloro-1H-pyrazol-1-yl)ethyl)-3H-imidazo[4,5-b]pyridin-5-yl)piperidin-3-yl)(pyrrolidin-1-yl)methanone (WO 2013150416, Example 196-A) for complete inhibition of DGAT2 was subtracted from all reactions. Inhibitors were tested at eleven different concentrations to generate IC50 values for each compound. The eleven inhibitor concentrations employed typically included 50, 15.8, 5, 1.58, 0.50, 0.16, 0.05, 0.016, 0.005, 0.0016, and 0.0005 μM. The data were plotted as percentage of inhibition versus inhibitor concentration and fit to the equation, y=100/[1+(x/IC50)z], where IC50 is the inhibitor concentration at 50% inhibition and z is the Hill slope (the slope of the curve at its inflection point). Table 3 below provides the IC50 values of the Examples for inhibition of DGAT2 in accordance with the above-described assay. Results are reported as geometric mean IC50 values.
Affinity data for this assay
 

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