| Assay Method Information | |
| | PHD enzymatic assay |
| Description: | The PHD enzymatic assay was performed in 0.5 ml of reaction mixture containing the following: purified PHD2181-417 polypeptide (3 μg), synthetic HIF-1α peptide comprising residues [KNPFSTGDTDLDLEMLAPYIPMDDDFQLRSFDQLS] (10 μM, California Peptide Research Inc., Napa, Calif.), and [5-14C]-2-oxoglutaric acid (50 mCi/mmol, Moravek Chemicals, Brea, Calif.) in reaction buffer (40 mM Tris-HCl, pH 7.5, 0.4 mg/ml catalase, 0.5 mM DTT, 1 mM ascorbate) for 10 minutes. Compounds were pre-incubated for 30 min before starting the reaction (all test compounds were dissolved at 10 mM in 100% DMSO (w/v) and were tested with final compound concentrations at 100 μM in 1% DMSO (w/v)). The reaction was stopped by addition of 50 μl of 70 mM H3PO4 and 50 μl of 500 mM NaH2PO4, pH 3.2. Detection of [14C]-succinic acid was achieved by separating from [5-14C]-2-oxoglutaric acid by incubating the reaction mixture with 100 μl of 0.16 M DNP prepared in 30% perchloric acid. Next, 50 μl of unlabeled 20 mM 2-oxoglutaric acid/20 mM succinic acid, serving as carrier for the radioactivity, was added to the mixture, and was allowed to proceed for 30 minutes at room temperature. The reaction was then incubated with 50 μl of 1 M 2-oxoglutaric acid for 30 additional minutes at room temperature to precipitate the excess DNP. The reaction was then centrifuged at 2800×g for 10 minutes at room temperature to separate [14C]-succinic acid in the supernatant from the precipitated [14C]-dinitrophenylhydrazone. Fractions of the supernatant (400 μI) were counted using a beta counter (Beckman Coulter, Fullerton, Calif.). Inhibition of PHD2181-417 activity was measured as a decrease in succinic acid production. The IC50 values were estimated by fitting the data to a three-parameter logistic function using GraphPad Prism, version 4.02 (Graph Pad Software, San Diego, Calif.). |
| Affinity data for this assay | |
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