| Assay Method Information | |
| | Modified Recombinant Enzyme Assay |
| Description: | Glutaminase reaction buffer was prepared [50 mM Tris-HCl pH 8.8, 150 mM K2HPO4, 0.25 mM EDTA, 0.1 mg/ml BSA (Calbiochem no. 2960), 1 mM DTT, 2 mM NADP+(Sigma Aldrich no. N5755), and 0.01% TX-100] and used to make 3×-enzyme-containing solution, 3×-substrate-containing solution, and 3×-inhibitor-containing solution (see below) Inhibitor-containing solution was made by diluting DMSO stocks of compounds into the glutaminase reaction buffer to create a 3× inhibitor solution containing 6% DMSO. 3×-enzyme-containing solution was made by diluting recombinant glutaminase and GDH from Proteus species (Sigma Aldrich no. G4387) into glutaminase buffer to create a 6 nM glutaminase plus 18 units/mL GDH solution. A 3× substrate solution containing either Gln, Glu, or NADPH was made by diluting a stock of Gln (Sigma Aldrich no. 49419), Glu (Sigma Aldrich no. 49449), or NADPH (Sigma Aldrich no. N1630) into glutaminase reaction buffer to create a 3×-substrate solution. Reactions were assembled in a 384-well low-volume black microtiter plates (Molecular Devices no. 0200-5202) by mixing 5 μL of inhibitor-containing solution with 5 μL of substrate-containing solution followed by 5 μL of enzyme-containing solution when no preincubation was required. When time-dependent effects of compound inhibition were tested, enzyme-containing solution was treated with inhibitor-containing solution for the indicated time prior to addition of substrate-containing solution. |
| Affinity data for this assay | |
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