DBCO-NHCO-PEG4-amine is a carboxyl-reactive building block with extended PEG spacer arm. The hydrophilic PEG spacer arm improves water solubility. In the presence of of activators (e.g. EDC, or HATU), this reagent can be used to derivatize carboxyl groups or activated esters (e.g. The NHS ester) through a stable amide bond. DBCO is commonly used for copper-free Click Chemistry reactions. Reagent grade, for research purpose. Please contact us for GMP-grade inquiries.