Bis-PEG1-NHS ester is a PEG linker containing two NHS ester groups. The hydrophilic PEG spacer increases solubility in aqueous media. The NHS ester can be used to label the primary amines (-NH2) of proteins, amine-modified oligonucleotides, and other amine-containing molecules. Reagent grade, for research purpose. Please contact us for GMP-grade inquiries.