N-(2,2,2-Trifluoroacetyl)-3-[(2-aminoethyl)dithio]propanoic acid is a cleavable linker containing a carboxylic acid. The terminal carboxylic acid can be reacted with primary amine groups in the presence of activators (e.g. EDC, or DCC) to form a stable amide bond. The disulfide bond can be cleaved via reduction reactions.