Capzimin

Kinase experiment:

Fluorescence polarization assays are performed in low-volume 384 well solid black plates in quadruplicate. The assays are performed in buffer containing 50 mM Tris-HCl pH7.5, 1mM MgCl2, 50 μM ATP, 1 mM DTT and 0.01% NP-40. The components for the assay are added in the follow sequence: 1) 5 μL compound (Capzimin, et al.) (in 3% DMSO) at different concentrations, 2) 5 μL of diluted human 26S proteasome, and 3) 5μL of substrate (3 nM Ub4- peptideOG). 100 μM Zn(cyclen)2+ is present in the titration reaction for the experiments performed with Zn(cyclen)2+. Fluorescence polarization is measured at 30°C with excitation at 480 nm and emission at 520 nm. Collected data is normalized to DMSO control and fitted to a dose-response curve to determine the IC50 value[1].

Cell experiment:

HCT116 cells are treated with different concentrations of 3021 or Capzimin for 72 hours in normal or low serum medium and then mixed with CellTiter-Glo reagent to estimate cell proliferation. Measured luminescence values are normalized to DMSO control and data are fitted to a dose-response equation to determine the GI50[1].

References:

[1]. Li J, et al. Capzimin is a potent and specific inhibitor of proteasome isopeptidase Rpn11. Nat Chem Biol. 2017 May;13(5):486-493.