Bromo-PEG4-CH2CO2tBu linker contains a bromide group and a t-butyl protected carboxyl group. The PEG spacer increases the aqueous solubility of the resulting compound. The bromide (Br) is a very good leaving group for nucleophilic substitution reactions. The t-butyl protected carboxyl group can be deprotected under acidic conditions.
Axispharm offers 3000+ PEG Linkers with high purity. Different kinds of PEG Reagents may be available by custom synthesis.