Site – specific PEGylation of rHuEPO and evaluation of its biological activity and stability

Document Type : Original Article


Despite the critical role of erythropoietin (EPO) as therapeutic agent in treatment of anemia, its consumption is limited due to several disadvantages including the product short half-life, immunogenicity and susceptibility to proteolytic degradation. To overcome these drawbacks efficient methods such as site-specific PEGylation have been developed among witch N-terminal PEGylation has found more interest due to its capability to preserve the protein native structure. In this study a site-specific PEGylation of rHuEPO is conducted and the biological activity and the stability of the modified protein are evaluated. rHuEPO was N-Terminally PEGylated with PEG-propionaldehyde through Schiff base reaction in acidic pH conditions. The product was then purified to yield in mono N-terminally PEGylated EPO. The resultant PEG-EPO and unmodified EPO was then compared to evaluate the consequence of the pegylation process. The results showed that despite the lower activity of PEG-EPO relative to the unmodified EPO, the earlier gained improved stability as a consequence of site-specific PEGylation. This observation provides further indication for the usefulness of PEGylation approach to enhance characteristics of erythropitein.