N-(Azido-PEG3)-NH-PEG3-acid is an aqueous soluble PEG reagent with a terminal azide group and terminal carboxylic acid. the secondary amine NH group is reactive with NHS ester, The terminal carboxylic acid can react with primary amine groups in the presence of activators (e.g. EDC, or HATU) to form a stable amide bond. The azide group can participate in Click Chemistry.
