DBCO-NHCO-PEG5-NHS ester is a PEG derivative containing NHS ester that is able to react specifically and efficiently with primary amines such as the side chain of lysine residues or aminosilane-coated surfaces at neutral or slightly basic condition to form a covalent bond. The hydrophilic PEG spacer arm improves water solubility and can also provide a long and flexible connection that minimizes steric hindrance during ligation. DBCO is commonly used for copper-free Click Chemistry reactions.
