FIG. 4.

MALDI-TOF-MS of peptide-N4-(N-acetyl-β-glucosaminyl) asparagine amidase F (PNGase F)-released complex-type N-glycans. Glycoproteins were isolated from undifferentiated and adipogenically differentiated MSCs. After isolation of high-mannose- and hybrid-type N-glycans by Endo H digestion, digested glycopeptides were subjected to PNGase F digestion to release complex-type N-glycans, permethylated and measured by MALDI-TOF-MS. A representative mass spectrum of PNGase F-released N-glycans of undifferentiated human MSCs is shown together with the 70 most abundant structures. Polyhexose contaminations are marked with asterisks and are negligible. Unidentified peaks were marked with complex asterisks. The black square represents N-acetylglucosamine, gray circle mannose, white circle galactose, black triangle fucose and black diamond N-acetylneuraminic acid.