title: Analysis of carbohydrate heterogeneity in a glycoprotein using liquid chromatography/mass spectrometry and liquid chromatography with tandem mass spectrometry.
abstract: High-performance liquid chromatography with on-line electrospray ionization mass spectrometry (ESI-LC/MS) was investigated for the analysis of carbohydrate heterogeneity using RNase B as a model glycoprotein. Oligosaccharides released from RNase B with endoglycosidase H were reduced and separated on a graphitized carbon column (GCC). GCC-HPLC/MS in the positive-ion mode was successful in the identification of one Man5GlcNAc, three Man6GlcNAc, three Man7GlcNAc, three Man8GlcNAc, one Man9GlcNAc, and an oligosaccharide having six hexose units (Hex) and two N-acetylhexosamine units (HexNAc). The branch structures of the three Man7GlcNAc isomers were determined by liquid chromatography with tandem mass spectrometry (LC/MS/MS). LC/MS/MS analysis was shown to be useful for the detection and identification of a trace amount of Hex6HexNAc2 alditol as a hybrid-type oligosaccharide. Its structure was confirmed by the combination of LC/MS with enzymatic digestion using beta-galactosidase and N-acetyl-beta-glucosaminidase. The relative quantities of high-mannose-type oligosaccharides in RNase B detected by ESI-LC/MS are in reasonable agreement with those by UV, high-pH anion-exchange chromatography with pulsed amperometric detection, fluorophore-assisted carbohydrate electrophoresis. Our results indicate that LC/MS and LC/MS/MS can be utilized to elucidate the distribution of oligosaccharides and their structures, which differ in molecular weight, sugar sequence, and branch structure.
authors.affiliation: Division of Biological Chemistry and Biologicals, National Institute of Health Sciences, 1-18-1 Kamiyoga, Tokyo, Setagaya-ku, 158-8501, Japan.
authors.forename: N
authors.initials: N
authors.lastname: Kawasaki
authors.forename: M
authors.initials: M
authors.lastname: Ohta
authors.forename: S
authors.initials: S
authors.lastname: Hyuga
authors.forename: O
authors.initials: O
authors.lastname: Hashimoto
authors.forename: T
authors.initials: T
authors.lastname: Hayakawa
mesh_terms: D000818:Animals; D002240:Carbohydrate Sequence; D002241:Carbohydrates / Q000032:analysis* / Q000737:chemistry; D002417:Cattle; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D006023:Glycoproteins / Q000737:chemistry*; D013058:Mass Spectrometry / Q000379:methods*; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000032:analysis / Q000737:chemistry; D012260:Ribonucleases / Q000737:chemistry; D013402:Sugar Alcohols / Q000032:analysis
chemical_list: D002241:Carbohydrates; D006023:Glycoproteins; D009844:Oligosaccharides; D013402:Sugar Alcohols; D012260:Ribonucleases; C029600:ribonuclease B