bis PEG5 acetic acid linker contains two terminal carboxylic acid groups. The PEG spacer increases the aqueous solubility of the resulting compound. The terminal carboxylic acids can undergo sequential amide couplinng in the presence of activators (e.g. EDC, or DCC) with two amine containing biomolecules.
AxisPharm offers 4000+ PEG Linkers with high purity. Different kinds of PEG Reagents may be available by custom synthesis.