The high-purity CbzNH-PEG3-CH2CH2NH2 provided by Axispharm is a peg derivative containing a Cbz-protected amine at one end and a free amine group at the other end. The amino group reacts with a carboxylic acid and an activated ester to form an amide bond. The Cbz group can be deprotected to form the free amine, which can then be subjected to a second amide coupling.
AxisPharm offers 5000+ PEG Linkers with high purity. Different kinds of PEG Reagents may be available by custom synthesis.