Methyltetrazine-PEG4-STP Ester is an amine-reactive, water-soluble labeling reagent used to modify proteins, antibodies, and other amine-containing biopolymers in aqueous media. Methyltetrazine-PEG4-STP Ester undergoes hydrolysis in aqueous media at much slower rate compared to Methyltetrazine-Sulfo NHS Ester allowing for more efficient labeling of biomolecules in aqueous media. The PEG spacer arm provides a long and flexible connection that minimizes steric hindrance involved with ligation to complementary TCO-containing molecules. The aqueous solubility of this reagent is substantially enhanced by a hydrophilic polyethylene glycol (PEG) spacer arm.
4-Sulfo-2,3,5,6-tetrafluorophenyl (STP) esters is another type of carboxylic acid derivative that react with primary amines forming covalent amide bond. The amine linkage bond is identical to one formed by the reaction between primary amines and NHS esters or sulfo-NHS esters. However, in most cases, STP ester displays much better stability toward hydrolysis in aqueous media resulting in more efficiency and better reproducible labeling of biopolymers.
Axispharm offers 3000+ PEG Linkers with high purity. Different kinds of PEG Reagents may be available by custom synthesis.