endo-BCN-PEG4-NHS ester can be used to label the primary amines (-NH2) of proteins, amine-modified oligonucleotides, and other amine-containing molecules. The BCN group enables copper free click chemistry with azide-tagged biomolecules. The hydrophilic PEG spacer increases solubility in aqueous media. Reagent grade, for research purpose. Please contact us for GMP-grade inquiries.