PEG21-Tos linker bears a hydroxyl group and a tosyl group. The PEG spacer increases the aqueous solubility of the resulting compound. The hydroxyl group enables further derivatization or replacement with other reactive functional groups. The tosyl group is a very good leaving group for nucleophilic substitution.
Axispharm offers 3000+ PEG Linkers with high purity. Different kinds of PEG Reagents may be available by custom synthesis.