NMS-873 

The ATPase activity and the kinetic parameters of recombinant wild-type VCP and its mutants are evaluated by monitoring ADP formation in the reaction, using a modified NADH-coupled assay46. As ADP and NADH are ATP-competitive inhibitors of VCP ATPase activity, the standard protocol for the NADH-coupled assay is modified into a two-step procedure. In the first part, an ATP-regenerating system (40 U/mL pyruvate kinase and 3 mM phosphoenolpyruvate) recycles the ADP produced by VCP activity, keeps the substrate concentration constant (thus preventing product inhibition) and accumulates a stoichiometric amount of pyruvate. In the second part, the VCP enzymatic reaction is quenched with 30 mM EDTA and 250 μM NADH and stoichiometrically oxidized by 40 U/mL lactic dehydrogenase to reduce accumulated pyruvate. The decrease of NADH concentration is measured at 340 nm using a Tecan Safire 2 reader plate. The assay is performed in 96- or 384-well UV platesin a reaction buffer with 50 mM Hepes, pH 7.5, 0.2 mg/mL BSA, 10 mM MgCl₂ and 2 mM DTT.

MCE has not independently confirmed the accuracy of these methods. They are for reference only.

Cells are seeded at 1,600 cells per well in 384-well white clear-bottom plates. Twenty-four hours after seeding, cells are treated with the compounds (eight dilution points, in duplicate, for each compound) and incubated for an additional 72 h at 37°C under a 5% CO₂ atmosphere. Cells are then lysed, and the ATP content in each well is determined using a thermostable firefly luciferase-based assay from Promega as a measure of cell viability. IC₅₀ values are calculated using the percentage of growth of treated cells versus the untreated control.

MCE has not independently confirmed the accuracy of these methods. They are for reference only.

• [1]. Paola Magnaghi, et al. Covalent and allosteric inhibitors of the ATPATP ase VCP/p97 induce cancer cell death. Nat Chem Biol. 2013 Jul 28. doi: 10.1038/nchembio.1313.  [Content Brief]