m-PEG-Succinimidyl Glutarate(mPEG-SG), MW 2K is a cleavable ester linker between the PEG polymer chain and the NHS ester, and the hydroxyl terminus is activated to an SG group that can bond to the free amino group of the active drug.
AxisPharm offers 5000+ PEG Linkers with high purity. Different kinds of PEG Reagents may be available by custom synthesis.