phthalimide-PEG2-bromide linker is a protected amine linker. The phthalimide reacts efficiently with hydrazine to relsease a primary group quantitatively, which can be used to conjugate with carboxylic acid and active ester bearing biomolecules. Bromo is readily replaced by nucleophiles such as amine and thiol, making it a good tool for cysteine thiol labelling.
AxisPharm offers 4000+ PEG Linkers with high purity. Different kinds of PEG Reagents may be available by custom synthesis.