N-(Tos-PEG4)-N-bis(PEG4-t-butyl ester) is a branched PEG linker with a Tos-PEG4 branch and two PEG4-t-butyl ester groups attached to a central nitrogen. The tosyl group can be easily replaced by thiol and amino group through a nucleophilic substitution.The t-butyl ester can be removed under acidic condition to form free acid groups, which can undergo sequential amide coupling to conjugate with two amine-bearing biomolecules. The hydrophilic PEG linker together with the central tertiary amine drastically imporves the water solubility of the resulting compound.
AxisPharm offers 4000+ PEG Linkers with high purity. Different kinds of PEG Reagents may be available by custom synthesis.