Biophysical investigation and conformational analysis of p38α kinase inhibitor doramapimod and its analogues

Abstract

Doramapimod (BIRB 796) is a potent inhibitor of p38α mitogen-activated protein kinase. It contains an aryl-pyrazole scaffold as a pharmacophore critical for binding. The aryl-pyrazole scaffold is not planar and adopts an out-of-plane conformation, which is described by the torsion angle θ. In this letter, we report the chemical synthesis and biophysical characterization of different analogues of doramapimod (3–12) exhibiting distinctly different aryl-pyrazole torsion angle θ values. The torsion angle θ values of the synthesized analogues (3–6) were determined by crystal structural analysis and the binding affinities to p38α kinase investigated by microscale thermophoresis. Our results unveil a clear correlation between kinase binding and the torsion angle θ of tested doramapimod analogues, highlighting the importance of inhibitor conformation for protein binding.