The heterobifunctional, crossslinker succinimidyl acetylthioacetate (SATA) enables one to covalently link two target groups. The succinimidyl ester chemically reacts with primary amines and after mild reduction to remove the protecting group, the thiol can form a disulfide with available thiols. Crosslinking reagents are useful for probing the spatial relationships and interactions within and between biomolecules.