The ureido-3,3′-dipropionic acid bis(hydroxysuccinimide) ester, is a medium length MS-cleavable urea-based lysine-lysine reactive homobifunctional cross-linkers, featuring a C3-arm. At neutral or slightly basic pH, it irreversibly crosslinks the neighbouring lysine groups. The presence of the symmetrical urea moiety which is prone to collision-induced dissociation allows for the unambiguous distinguishing of crosslinks in tandem CID-MS experiments.
