At the forefront of any drug discovery program, is the ability to understand the polypharmacological profiles of a given active pharmaceutical ingredient. Polypharmacology usually manifest itself through increase in therapeutic efficacy when properly exploited or may drive off-target toxicity that may disqualify chemical entities as potential drug candidate. Many drugs in diverse therapeutic areas possess known polypharmacology, however, global molecular targets of even common drugs, such as the non-steroidal anti-inflammatory drugs (NSAIDs), remain little understood. Here, we present a global binding site identification platform for the direct in cellulo charac- terization of NSAID binding sites. The platform uses (1) photochemical conjugation of NSAID derivatives in the whole proteome, (2) enrichment of the binding sites, for (3) targeted mass spectrometry-based assignment. Using this approach, we identified the NSAID “interactome” consisting of over 1000 enriched proteins and directly characterized nearly 200 binding sites in Jurkat and K562 cells. The enriched proteins were often identified as parts of complexes, including known targets of NSAID activity (e.g., NF-KB) and novel interactions (e.g., AP-1, proteasome). These data further revealed a binding site hotspot of NSAIDs on nucleosomes. This approach to characterize NSAID-targets can be applied to map out the binding sites of visually any small molecule.

Discovery of a binding site hot spot for non-steroidal anti- inflammatory drugs on the cellular nucleosome

255th National Meeting (2018)

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