Polyethylene Glycol (PEG) is a polymer of ethylene oxide available in size variants from 400 Da to 40 kDa. It is nonionic, nontoxic, biocompatible, strong, hydrophilic and has a large exclusion volume in aqueous solution. PEG has a number of industrial and biomedical applications. The modification of a biopharmaceutical with PEG increases its hydrodynamic radius, reduces immunogenicity and proteolytic cleavage. In particular, therapeutic proteins are conj
