Primary Structure Analysis of rhEPO by MALDI-TOF-MS

Matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF-MS) is a rather new 'soft ionization' techniques. Because of its high sensitivity and accuracy, it has been widely used in detection and characterization of macromolecules such as peptides, proteins and olignucleotides. It also has been applied successfully in the analysis of posttranslational modification of proteins, such as phosphorylation and glycosylation. Compared with the conventional chemical methods, mass spectrometry is simple, rapid and does not require radiolabeling. In this research, a systematic method to analyse glycoprotein by MALDI-TOF-MS was developed. A practical sample-recombinant human erythropoietin was analysed by the method. The molecular weight, content of carbohydrate and glycosylation sites of the glycoprotein were determined by MALDI-TOF-MS, combined with the endo-glycosidase digestion and peptide mapping. The experimental result shows that MALDI-TOF-MS is a very powerful technique in the characterization of glycosylation proteins.