DSG is a homobifunctional amine-specific crosslinking reagent based on NHS-ester reactive groups for selective conjugation of primary amines.DSG contains two NHS ester groups at both ends of a 5-carbon spacer that readily react towards primary amines at pH 7-9.DSG is not water soluble and must be dissolved in an organic solvent such as DMSO or DMF prior to use.DSG is membrane permeable and can be used for intracelular crosslinking.