Fmoc-NH-PEG4-CH2COOH contains an Fmoc-protected amine and a terminal carboxylic acid. The PEG spacer increases the aqueous solubility of the resulting compound. The Fmoc group can be deprotected under basic condition to form a free amine which can be used for further conjugations. The terminal carboxylic acid readily reacts with primary and secondary amine under EDC, DCC, HATU or other amide coupling conditions to form a stable amide bond.
AxisPharm offers 5000+ PEG Linkers with high purity. Different kinds of PEG Reagents may be available by custom synthesis.