Discrimination of granulocyte colony-stimulating factor isoforms by high-performance capillary electrophoresis

Rapid quantitative capillary zone electrophoresis method for monitoring the micro-heterogeneity of an intact recombinant glycoprotein

A simple high-resolution capillary zone electrophoresis (CZE) method capable of rapidly assessing the micro-heterogeneity of a 24 kDa molecular weight glycoprotein, has been developed. Separation is carried out using a bare silica capillary at a pH of 2.5 in a commercially available electrophoresis buffer system composed of triethanolamine and phosphoric acid. Over 30 peaks were detected within a run time of 15 min using a 27 cm capillary and approximately 60 peaks were detected using a 77 cm capillary. Although most of the peaks arise from differences in the oligosaccharide structures present on the one glycosylation site on this molecule, other forms of micro-heterogeneity due to the presence of the nonglycosylated form of this glycoprotein and various types of chemical degradation, e.g., deamidation, are also responsible for the multitude of peaks observed. Although the exact chemical identity of each peak in the resulting electropherogram of this glycoprotein is not known, useful information can be obtained for assessing comparability, stability, and batch consistency. Factors impacting the resolution, precision, accuracy, and robustness of the assay are also discussed along with inherent advantages and limitations associated with measuring the micro-heterogeneity of intact glycoproteins.

Characterization of recombinant human granulocyte colony stimulating factor (rHuG-CSF) by capillary zone electrophoresis, capillary isoelectric focusing electrophoresis and electrospray ionization mass spectrometry

Recombinant human granulocyte colony-stimulating factor (rHuG-CSF) is a hematopietic cytokine that stimulates and regulates the proliferation and differentiation of neutrophils. Glycosylated and non-glycosylated forms of rHuG-CSF cannot be distinguished by traditional biological assays. In addition, it is very difficult to characterize impurities of the same molecular weight in biologicals. In this study, non-glycosylated rHuG-CSF, two glycosylated rHuG-CSF isoforms and their commercial dosages were successfully separated by capillary zone electrophoresis (CZE) using 50mM Tricine containing 20mM NaCl and 2.5mM 1,4-diaminobutane (DAB) at pH 8.0, which could be employed for the qualitative discrimination assay of rHuG-CSF related products. CZE, capillary isoelectric focusing electrophoresis (CIEF), and mass spectrometry (MS) were used to effectively characterize non-glycosylated rHuG-CSF. It was found that proteins in the samples with different pIs in the CIEF profile could not be detected by CZE, while no difference was observed between these proteins and rHuG-CSF. Further analysis by electrospray ionization mass spectrometry with the resolution of 2000 showed that the components with different pIs in the non-glycosylated rHuG-CSF bulk sample are nearly equal in molecular weight. Therefore, it is necessary to combine several modern analytical techniques for quality control to get well-characterized biologicals.

Analysis of glycoproteins and the oligosaccharides thereof by high-performance capillary electrophoresis-significance in regulatory studies on biopharmaceutical products

This review describes the recent development in the analysis of glycoproteins using capillary electrophoresis with various separation techniques, and focuses especially on the analysis of recombinant glycoprotein pharmaceuticals. We include the analysis of glycoprotein multiforms (ie glycoform) as well as glycan analysis. The relationship between glycoprotein multiforms and oligosaccharide distributions in a glycoprotein sample is also discussed. Further, recent development in capillary electrophoresis-mass spectrometry is described.

Capillary electrophoresis of proteins 1999-2001

This review article with 223 references describes recent developments in capillary electrophoresis (CE) of proteins and covers papers published during last two years, from the previous review (V. Dolnik, Electrophoresis 1999, 20, 3106-3115) through Spring 2001. It describes the topics related to CE of proteins including modeling of the electrophoretic properties of proteins, sample pretreatment, wall coatings, improving selectivity, detection, special electrophoretic techniques, and applications.