t-Butoxycarbonyl-PEG3-NHS ester contains a t-butyl ester group and an NHS ester moiety. The PEG spacer increases the aqueous solubility of the resulting compound. The NHS ester readily reacts with primary and secondary amine bearing molecules (e.g. the side chain of lysine residues or aminosilane-coated surfaces) at neutral or slightly basic condition to form a covalent bond. The t-butyl group is removed under acidic conditions to form a free acid, which can under further conjugations.
AxisPharm offers 4000+ PEG Linkers with high purity. Different kinds of PEG Reagents may be available by custom synthesis.