| Assay Method Information | |
| | Biochemical Assay |
| Description: | Wild-Type IDH1: Enzymes catalyze the conversion of isocitrate to αKG. Wild-type IDH1 (National Center for Biotechnology Information, Accession: NP_001269316.1) and IDH2 (National Center for Biotechnology Information, Accession: EAX02082.1) proteins containing N-terminal His-tag are expressed in E. coli and purified using nickel affinity chromatography by methods commonly used and well known to those skilled in the art. The enzyme assays are carried out in V-bottom 96 well polypropylene plates containing 100 mM Tris-HCl buffer at pH 7.5, 1 mM DTT, 0.005% TRITON X-100, 120 mM NaCl. For the IDH1 wild-type assay isocitrate, NADP+ and MnCl2 are included at the concentrations of 85 μM, 50 μM and 20 μM respectively. For the IDH2 wild-type assay isocitrate, NADP+ and MnCl2 are included at the concentrations of 30 μM, 50 μM and 10 μM respectively. Inhibitors dissolved in a DMSO stock solution are diluted in the reaction mixture at a final DMSO concentration of 4%. The enzyme assay is terminated (quenched) by adding ACN (50:50) containing d (d6-αKG) as an internal standard for mass spectrometry analysis. Ten microliters of reaction mixture is combined with 100 μL of water, 50 μL of 1 M O-benzylhydroxylamine in pyridine buffer (8.6% pyridine, pH 5), and 50 μL of 1 M EDC in pyridine buffer. Following derivatization at room temperature for one hour, samples are extracted with EtOAc (600 μL). Four hundred L of the upper layer is removed, dried under heated nitrogen, and reconstituted with MeOH/water (1:1) (100 μL). Ten μL of derivatized sample is injected onto an LC-MS system consisting of a Shimadzu Prominence 20A HPLC system and a Thermo Quantum Ultra triple quadrupole mass spectrometer. |
| Affinity data for this assay | |
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