Assay Method Information

Assay Name:  Nitric Oxide Suppression Assay
Description:  RAW 264.7 cells were plated 1 day in advance of experiment at a concentration of 80,000 cells/well onto CellBIND 96 well plates (Corning, N.Y.) in a total volume of 100 μL. The next day, pre-treat cells with compounds (from 3 μM to 0.3 nM serially diluted in a 10 point curve) from a 10× stock by adding 10 μL per well in complete DMEM media containing 10% fetal calf serum. The plates were centrifuged for 3 minutes at 400×g at room temperature followed by 2 hour incubation at 37° C. The cells were then incubated overnight at 37° C. with 10 μL of the insult, interferon gamma (R&D Systems, Minneapolis, Minn.), from a 10× stock for a final concentration of 20 ng/mL. The plates were centrifuged for 3 minutes at 400×g at room temperature followed by 18 hour incubation at 37° C. The following day, transfer 50 μL cell culture supernatant from each well into a clear bottom 96 well plate and follow the instructions from Promega's Griess Detection Kit #G2930 (Madison, Wis.) which involves the addition of 50 μL of the provided sulfanilamide solution for a 5-10 minute incubation at room temperature. Next add 50 μL of the provided N-1-napthylethylenediamine dihydrochloride (NED) solution for a 5-10 minute incubation at room temperature and protected from light. If any air bubbles were introduced into the well, the plates need to be centrifuged for 5 minutes at 400×g at room temperature to avoid interference with absorbance readings. The plates were read for absorbance within 30 minutes with a filter between 520 nm and 550 nm.For the ability of compounds to suppress the increase in nitric oxide release, the percent maximal intensity of nitric oxide detected in each well was normalized to that induced by the peak value for 20 ng/mL of interferon gamma alone and plotted against the compound concentration to calculate IC50 values and to control for plate-to-plate variability. Concentration-response data were analyzed using GraphPad Prism (San Diego, Calif.).
Affinity data for this assay
 

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