Abstract
Most ligands for the Von Hippel-Lindau tumor suppressor (VHL) bind at the HIF-1α binding site. Ligands that bind to allosteric sites on VHL could be highly valuable for the field of protein degradation, therefore, a covalent hit identification campaign was run targeting Cys77 on VHL. Hit 2 bound selectively to Cys77 on VHL and did not alkylate the reactive Cys89 on Elongin B. It showed time- and concentration-dependent labeling, with a k (inact)/K (I) of 0.30 M(-1) s(-1), and does not affect binding at the HIF-1α site. This hit ligand was optimized to afford compound 15 which showed improved potency and labeling of VHL. An X-ray structure of a close analogue was determined revealing the compound binding in a shallow groove on the surface of VHL. These are the first small molecules that bind covalently to an allosteric site on VHL and provide a suitable starting point for further optimization.