The aldehyde group readily reacts with primary amines, aminooxy and hydrazide to form a reversible oxime or hydrazone linkage. If reduced, the oxime or hydrazone bonds are converted to more stable C-N bonds. The ester can be hydrolyzed to a free acid for conjugation with amine bearing biomolecules, such as the lysine residue of proteins.
Axispharm offers 3000+ PEG Linkers with high purity. Different kinds of PEG Reagents may be available by custom synthesis.