FSK (hydrochloride)

FSK hydrochloride is fluorosulfonyloxybenzoyl-l-lysine, with a long and flexible aryl fluorosulfate-containing side chain that can reach protein sites that are difficult to reach by covalent linkage. FSK hydrochloride is a modified nanomolecule that targets the epidermal growth factor receptor (EGFR), creating a covalent binding that results in irreversible binding. FSK hydrochloride captures unknown enzyme-substrate interactions in living cells through genetically encoded chemical cross-linking, targeting residues beyond Cys, and cross-linking at the binding periphery. FSK hydrochloride enables the construction of bioreactive SuFEx systems for creating covalent bonds in different proteins in vitro and in vivo[1].