Inhibition of human cytomegalovirus DNA polymerase (95 uL) activity in a solution containing 6.4 mM HEPES (pH 7.5), incubation for 12 minutes at 26 degrees C
HCMV Polymerase LANCE TR-FRET Assay: The assay conditions are the following: 10 mM HEPES pH 7.5, 25 mM KCl, 7.5 mM NaCl, 5 mM MgCl2, 0.2 mg BSA/mL, 1 mM TCEP, 1.5% glycerol, 5% DMSO, 235 nM dATP, 350 nM dCTP, 350 nM dGTP, 235 nM dTTP, 12 nM biotin-16-dUTP, 23.5 nM Dig-primer/template, 2 nM GST-UL54. The assay volume is 10 μL. Each reagent is added as follow: 4 μL a+3 μL b+3 μL c; a: compound diluted in compound dilution buffer to obtain 12.5% DMSO; b: enzyme (GST-UL54) in 10 mM Hepes pH 7.5, 25 mM KCl, 5 mM MgCl2, 25 mM NaCl, 5% Glycerol, 0.67 mg BSA/mL, 1 mM TCEP w/o DMSO (2 nM GST-UL54 is present in the assay); c: substrate in 10 mM HEPES pH 7.5, 25 mM KCl, 5 mM MgCl2, 1 mM TCEP, 783 nM dATP, 1166 nM dCTP, 1166 nM dGTP, 783 nM dTTP, 40 nM biotin-16-dUTP, 78 nM Dig-primer (5'-/Dig/AGC TCG TTT AGT GAA CC-3')/template (5'-GAG GTC AAA ACA GCG TGG ATG GCG TCT CCA GGC GAT CTG ACG GTT CAC TAA ACG AGC T-3') w/o DMSO. The primer and template are annealed in 10 mM Tris-HCl pH 7.5, 50 mM NaCl at a respective concentration of 50 μM. They are incubated at 95 °C. for 5 min in a dry batch block. The block is removed from the dry bath and allowed to cool to RT. Aliquots are made and stored at −20 °C. To perform the assay, 3 μL of the enzyme solution is added to columns 2-12 and 14-24. The enzyme is substituted by the blank solution (b solution without enzyme) for columns 1 and 13 (blanks). The plate is centrifuged at 200×g for 30 sec. 3 μL of substrate solution is added to each well. The plate is centrifuged at 200×g for 30 sec. Plates are incubated at 37 °C. for 30 min. 5 μL of conjugate solution is added (25 mM Hepes pH 7.5, 0.1 M NaCl, 0.25% Tween-20, 1 mg/mL BSA, 12 mM EDTA, 24 nM Sreptavidin-APC, 342 ng/mL Anti-Dig-Europium). The plates are incubated at RT for at least 120 min. The signal is read on the Envision plate reader (Perkin-Elmer) or equivalent.
HCMV Polymerase Scintillation Proximity Assay: The assay conditions are the following: 10 mM HEPES pH 7.5, 25 mM KCl, 7.5 mM NaCl, 5 mM MgCl2, 0.2 mg BSA/mL, 1 mM TCEP, 1.5% glycerol, 2 μM dTTP, 90 nM 3H-dTTP (minor variations in concentration are possible due to specific activity of stock), 26 nM Poly(dA)/190 nM BioTEG-dT19; 5% DMSO. The assay volume is 30 μL. Each reagent is added at a 3× conc.: 10 μL a+10 μL b+10 μL c; a: compound diluted in 10 mM Hepes pH 7.5, 25 mM KCl, 5 mM MgCl2, 1 mM TCEP with 15% DMSO; b: enzyme (GST-UL54) in 10 mM Hepes pH 7.5, 25 mM KCl, 5 mM MgCl2, 22.5 mM NaCl, 4.5% Glycerol, 0.6 mg BSA/mL, 1 mM TCEP w/o DMSO (1 nM GST-UL54 is present in the assay); c: substrate in 10 mM Hepes pH 7.5, 25 mM KCl, 5 mM MgCl2, 1 mM TCEP, 6 μM dTTP, 270 nM 3H-dTTP, 78 nM Poly(dA)/570 nM BioTEG-dT19 w/o DMSO. To perform the assay, 10 μL enzyme solution is added to columns 2-12 and 14-24. The enzyme is substituted by the blank solution (b solution without enzyme) for columns 1 and 13 (blanks). The plate is centrifuged at 200×g for 30 sec. 10 μL of substrate solution is added to each well. The plate is centrifuged at 200×g for 30 sec. The plates are incubated at 37 °C. for 40 min. To stop the reaction, 25 μL of SPA beads (5 mg/mL in 0.5 M EDTA) are added and mixed by pipetting up and down. The plates are incubated at RT for at least 15 min. 35 μL of 5 M CsCl is added to the bottom of each well. TopSeal is applied to the plate and the plate is incubated at RT for at least 90 min prior to reading. The signal is read on TopCount plate reader (Perkin-Elmer) or equivalent.