[Study on evaluating methods for the quality control of glycoprotein products. (IV)--erythropoietin products. Part 4]

We have previously reported on peptide mapping of recombinant human erythropoietin (rhEPO) by liquid chromatography/mass spectrometry (LC/MS). Using this method, both peptides and glycosylation at each glycosylation site can be elucidated based on the mass chromatogram and mass spectrum. In this study, we evaluated the mass spectrometric peptide mapping with regard to its use in comparability assessment of both protein parts and carbohydrates parts in glycoprotein products. Models of closely related glycoprotein products used in this study are rhEPOs produced from three different sources. We demonstrated that the mass spectrometric peptide mapping can elucidate the identity of protein part, and differences in site-specific carbohydrates heterogeneity due to acetylation and sulfation among the three rhEPOs. Our method can thus be useful in comparability assessment of therapeutic glycoproteins.