Incomplete protein packing as a selectivity filter in drug design.

The conservation of structure across paralog proteins promotes alternative protein-ligand associations often leading to side effects in drug-based inhibition. However, sticky packing defects are typically not conserved across paralogs, making them suitable targets to reduce drug toxicity. This observation enables a strategy for the design of highly specific inhibitors involving ligands that wrap nonconserved packing defects. The selectivity of these inhibitors is evidenced in affinity assays on a cancer-related pharmacokinome: a powerful inhibitor is redesigned by using the wrapping technology to enhance its selectivity and affinity for a target kinase. In this way, the packing defects of a soluble protein may be used as selectivity filters for drug design.