t-Boc-N-amido-PEG4-(CH2)3CO2H linker contains a terminal carboxylic acid and Boc-protected amino group. The PEG spacer increases the aqueous solubility of the resulting compound. 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. The Boc group can be deprotected under mild acidic conditions to form the free amine, which can undergo amide coupling with carboxylic acid bearing biomolecules.
AxisPharm offers 5000+ PEG Linkers with high purity. Different kinds of PEG Reagents may be available by custom synthesis.