TCO-NHS contains a TCO moiety and a NHS ester. The hydrophilic PEG spacer can increase water-solubility and a decreases steric hindrance during ligation. This NHS ester site can be used to label antibodies, proteins and other primary amine-containing macromolecules and the TCO end can be used to conjugate with tetrazine tagged biomolecules.
Axispharm offers 3000+ PEG Linkers with high purity. Different kinds of PEG Reagents may be available by custom synthesis.