Mal-amido-PEG2-TFP ester is PEG linker containing a maleimide and TFP ester end group. Maleimide groups are reactive with thiols between pH 6.5 and 7.5. The TFP ester can react with primary amine groups and is also less susceptible to undergo hydrolysis compared to NHS ester. The hydrophilic PEG chains increase the water solubility of a compound in aqueous media. Longer PEG chains have improved water solubility relative to shorter PEG chains.
