S-acetyl-PEG3-acid is a PEG linker containing a sulfur acetyl group and a terminal carboxylic acid. The sulfur acetyl group can be deprotected to produce a thiol moiety. The terminal carboxylic acid can react with primary amines in the presence of EDC or HATU to produce amide bonds. The hydrophilic PEG linker increase the water solubility of the compound in aqueous media.
