Kinase experiment:

The cloning, expression and purification of USP21 from BL21 (DE3) bacteria are performed using standard molecular biology techniques. USP2, USP5, USP7, USP8, USP28, USP47, Ub-PLA2 (Ub-CHOP) and Ub-EKL (Ub-CHOP2) are generated. Caspase 3 and the caspase 3 substrate DEVD-Rh110 are used. Deubiquitylating enzyme, cathepsin B and 20S proteasome chymotrypsin like protease activities are measured. Caspase 3 activity is determined using a similar protocol. Briefly, dose ranges of compound (including USP7/USP47 inhibitor) are incubated with caspase 3 for 30 minutes before the addition of DEVD-Rh110 and reading on a fluorometric plate reader using excitation and emission maxima of 485 nm and 531 nm respectively. The final concentrations of caspase 3 and DEVD-Rh110 are 2 nM and 100 nM respectively[1].

USP7/USP47 inhibitor(compound 14) is a selective USP7 (EC50= 0.42 μM)/USP47 (EC50= 1.0 μM) inhibitor but does not inhibit caspase 3, calpain 1, 20S proteasome, and a panel of representative USPs (USP2, USP5, USP8, USP21, and USP28; EC50 > 31.6 μM Selective Dual Inhibitors of the Cancer-Related Deubiquitylating Proteases USP7 and USP47. compound 14 exhibits enhanced potency against HCT-116 cells. treatment of cells with compound 14 resulted in an increase in p53 and an appreciable induction of p21 protein over the DMSO control. Thus, compound 14 penetrated the cells and modulated p53 and p21 as expected for a USP7 inhibitor.