Discovery and characterization of MAPK-activated protein kinase-2 prevention of activation inhibitors.

Two structurally distinct series of novel, MAPK-activated kinase-2 prevention of activation inhibitors have been discovered by high throughput screening. Preliminary structureactivity relationship (SAR) studies revealed substructural features that influence the selective inhibition of the activation by p38 alpha of the downstream kinase MK2 in preference to an alternative substrate, MSK1. Enzyme kinetics, surface plasmon resonance (SPR), 2D protein NMR, and X-ray crystallography were used to determine the binding mode and the molecular mechanism of action. The compounds bind competitively to the ATP binding site of p38 alpha but unexpectedly with higher affinity in the p38 alpha-MK2 complex compared with p38 alpha alone. This observation is hypothesized to be the origin of the substrate selectivity. The two lead series identified are suitable for further investigation for their potential to treat chronic inflammatory diseases with improved tolerability over previously studied p38 alpha inhibitors.