Biotin-PEG2-acid contains a biotin and a carboxylic acid group. The hydrophilic PEG spacer improves the water solubility of biotinylated molecule and the distantly linked carboxylic acid allows extra flexibility in the resulting conjugated biomolecule.
Axispharm offers 3000+ PEG Linkers with high purity. Different kinds of PEG Reagents may be available by custom synthesis.