Chemical and biological properties of polymer-modified proteins.

Modification with polymers such as polyethylene glycol (PEG) can increase circulating lifetime, reduce immunogenicity and simplify the handling of pharmaceutical proteins. These benefits are currently exploited in six marketed polymer-modified protein therapeutics and about a dozen product candidates in clinical trials. However, traditional protein modification techniques are restricted by the limited control over polymer structure and the location and number of polymer attachment sites. New technology, in the form of chemical protein synthesis and the generation of precision polymers, has been applied to generate synthetic erythropoiesis protein (SEP). This promising treatment for anaemia has been synthesised with precision polymer modification methodology to improve the target protein pharmaceutical. The chemical and biological properties of proteins prepared by both traditional and novel approaches are contrasted in this discussion of chemical protein synthesis and polymer modification in protein drug discovery.