Mal-PEG4-NHS ester is a PEG linker containing a maleimide group and an NHS ester group. 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. The maleimide group will react with a thiol group to form a covalent bond, enabling the connection of biomolecule with a thiol.
