Polyethylene glycol-conjugated pharmaceutical proteins

Polyethylene glycol (PEG)-conjugated proteins belong to a new class of biomolecules that are neither proteins nor polymers, but which are hybrids of the two. PEG conjugation of biopharmaceuticals is now common practice in efforts to achieve sustained clinical response. However, very little is known about the strategies and criteria used to produce a well-characterized pegylated biomolecule. In this review, the issues of pegylation reagent selection, reaction conditions, process considerations and purification will be addressed, as well as biochemical and biological characterizations. The isolation of positional isomers and the determination of pegylation sites will also be included.