Detailed Glycosylation Analysis of Therapeutic Enzymes Using Comprehensive 2D-LC–MS

The use of comprehensive two-dimensional liquid chromatography (LC×LC) coupled to mass spectrometry (MS) for characterizing glycosylation of therapeutic enzymes is presented. Recombinant human acid α-glucosidase (rhGAA) was digested and resulting peptides were separated by reversed-phase LC (RPLC) at high and low pH in, respectively, the first and second dimension. Glycopeptide peaks were then selectively detected and identified by MS operated in all-ion fragmentation mode. The study of first generation rhGAA (myozyme), expressed in Chinese hamster ovary (CHO) cells, and next-generation glyco-engineered rhGAA, produced in yeast cells to fine-tune the mannose-6-phosphate (M6P) content, is described.