Characterization of Recombinant Human Erythropoietin Isoforms by Capillary Isoelectric Focusing with Hydroxypropyl Cellulose-Coated Capillaries

Capillary isoelectric focusing (cIEF) has become a powerful method for protein analysis and has shown promising perspectives in biopharmaceutical research, because it allows fast and automated analysis of proteins with high resolution. Here, an improved cIEF system was set up for exploring better characterization of recombinant human erythropoietin (EPO) with hydroxypropyl cellulose (HPC)-coated capillaries and an offline fast and convenient desalting treatment for EPO real sample. With the cIEF system, several separation conditions for EPO isomers were optimized and high resolution results were obtained. The use of HPC-coated capillary columns allowed for no additive needed for the elimination of EOF. The cIEF system might be applied to further complementary characterization of EPO by comparison with LC and other modes. And the cIEF system was considered promising for online coupling with MS. Graphical Abstract