BocNH-PEG3-CH2CH2COONHS

t-Boc-N-amido-PEG3-NHS ester is a PEG linker containing an NHS ester and a t-Boc protected amine group. The hydrophilic PEG spacer increases the solubility of compounds in aqueous media. The t-Boc group can be deprotected under mild acidic conditions to form a free amine. The NHS ester can be used to label the primary amines (-NH2) of proteins, amine-modified oligonucleotides, and other amine-containing molecules.