CHEMBL5736697

Selectivity Screening (ERK2): Candidates for inhibitor selectivity characterization were chosen based on an initial single-timepoint commercial kinome profiling screen performed with inhibitor 17 (MELK-In-7) (KinomeScan, DiscoveRx, San Diego, Calif.), primary sequence relation to MELK, and laboratory availability. CHK1 and NUAK1 were purchased from SignalChem (Vancouver, BC). The NUAK2, CHK, and SAMS peptides were purchased from BioSyn (Lewisville, Tex.). The sequence of CHK and NUAK2 peptides are described elsewhere (Sanchez Y, et al. Science (New York, N.Y.). 1997; 277(5331):1497-1501; Scott J W, et al. Sci Rep. 2015; 5:14436). ERK2, AMPK, CAMKK2, and Ets1 were produced in house as previously described (Waas W F, Dalby K N. The Journal of biological chemistry. 2002; 277(15):12532-12540; Neumann D, et al. Protein Expr Purif. 2003; 30(2):230-237; Waas W F, Dalby K N. Protein Expr Purif. 2001; 23(1):191-197). Apparent KM values for ATP under specific assay conditions were determined using respective experimental conditions in Table 8 with varied ATP (0-1.28 mM). All selectivity dose-response assays were performed in kinase assay buffer (see Inhibitor Library Screen) with 2 mM DTT and 100 μM γ-32P-ATP with additional conditions listed in Table 8. IC50 and KM ATP values were subsequently used to calculate Ki (Equation 4). Relative selectivity was determined by comparing Ki Enzyme/Ki MELK (termed φ in Table 7). All IC50 and/or Ki data were fit using Prism® (GraphPad) using equations 2, 3, and 4, as appropriate. Standard error from linear regression data was propagated internally in Prism and taken into account in nonlinear regression to determine IC50 or Ki. 1 nM ERK2, 20 μM Ets-1 0.25-4 min 98 ± 14