A novel mass spectrometric procedure for the rapid determination of the types of carbohydrate chains present in glycoproteins: application to alpha-galactosidase I from Vicia faba seeds

Combined partial acid hydrolysis and electrospray ionization-mass spectrometry for the structural determination of oligosaccharides

A general oligosaccharide acid hydrolysis method, amenable to electrospray ionization mass spectrometry (ESI-MS), is described that allows for hydrolysis of glycosidic bonds for both hexose- and N-acetylhexosamine-containing oligosaccharides. The partial acid hydrolysis of oligosaccharides is obtained by using an acid-exchange resin as the acid catalyst. A ladder sequence of the glycan is produced in solution that is directly analyzed by ESI tandem mass spectrometry, employing both ion trap and Fourier transform ion cyclotron resonance mass spectrometers, to provide sequence and linkage information. Unlike traditional acid hydrolysis procedures, there is minimal degradation of monosaccharide residues or deacetylation of N-acetylhexosamines by employing this technique. It is further demonstrated that the stereochemistry of the released monosaccharides and the anomeric configuration within disaccharides is determined by direct derivatization of the hydrolysate with Zn(dien)-Cl2 followed by ESI-MS/MS.

Liquid secondary ion mass spectrometry analysis of permethylated, n-hexylamine derivatized oligosaccharides. Application to baculovirus expressed mouse interleukin-3

Reductive amination with n-hexylamine followed by permethylation was used as a procedure for the liquid secondary ion mass spectrometry (LSIMS) analysis of Asn-linked oligosaccharides. Initial experiments with this procedure were performed on maltoheptaose. These experiments show that exhaustive methylation at the newly formed secondary nitrogen forms a quaternary ammonium salt. When this is subjected to positive ion LSIMS, an abundant M(+) ion is observed. This procedure was applied to the Asn-linked oligosaccharides released from human transferrin and ribonuclease-B. The reductively aminated, permethylated mixture of oligosaccharides from ribonuclease-B afforded a positive ion LSI mass spectrum in which M(+) ions for Mans5-9GlcNAc2 could be assigned. The positive ion LSI mass spectrum obtained from the mixture of oligosaccharides isolated from human transferrin showed M(+) ions that could be assigned to both monosialylated and disialylated biantennary complex type oligosaccharides. Reductive amination followed by permethylation of the Asn-linked oligosaccharides isolated from baculovirus expressed mouse interleukin-3 produced in Bombyx mori gave a positive ion LSI mass spectrum in which the oligosaccharides could be assigned the monosaccharide composition Man2-4[Fuc]GlcNAc2 and Man2GlcNAc2. These are believed to be dimannose, trimannose, and tetramannose chitobiose core oligosaccharides, three of which are fucosylated.

Mass spectrometric determination of glycosylation sites and oligosaccharide composition of insect-expressed mouse interleukin-3

The primary structure of Baculovirus-expressed mouse interleukin-3 produced in infected Bombyx mori larvae was characterized by liquid secondary ion mass spectrometry and 252Cf-plasma desorption mass spectrometry in combination with selected protein microchemical reactions. Interleukin-3 was found to consist of at least two glycoprotein species of ca. 17,000 dalton. Characterization of tryptic and S. aureus V8 protease peptides by Edman degradation combined with plasma desorption mass spectrometry showed that two N-glycosylation sites. Asn-16 and Asn-86, were present. N-Glycan residues were shown by liquid secondary ion mass spectrometry and high-performance liquid chromatography to consist of mannose, fucose, and glucosamine. The presence of galactosamine indicated that O-glycosylated residues were present, in addition to the N-glycosylated residues. Glucose was also present, which indicated incomplete processing of the insect-expressed N-linked oligosaccharides.

Novel fast atom bombardment mass spectrometric procedures for glycoprotein analysis

We describe procedures, based upon fast atom bombardment mass spectrometry, for characterising the carbohydrate chains in glycoproteins and for determining sites of glycosylation. Strategies for rapidly screening glycoproteins to ascertain the types of sugar chains present and the degree of heterogeneity are presented. Protocols are given for sequencing O- and N-linked glycans. These strategies exploit simple purification steps and afford data at high sensitivity.

A mass spectrometric study of the structure of sterol carrier protein SCP2 from rat liver

The amino acid sequence of Sterol Carrier Protein2 (SCP2) isolated from rat has been investigated. Using a novel mass spectrometric mapping approach, the C-terminus was found to be extended beyond the previously published sequence. Carbohydrate analysis of SCP2 samples suggest the presence of tightly bound mannose oligosaccharide of 5-10 residues, although probably not in a glycoprotein linkage.

Field desorption tandem mass spectrometry of anthracycline antibiotics, cosmomycin A, B, A', B', C and D

Field desorption mass spectrometry was applied to a series of underivatized anthracycline, cosmomycins, to obtain fragment ions which were mass analysed using the linked scan technique without using collision activated dissociation. The daughter spectra of the various protonated compounds contain sugar sequence information which is in the mass spectra. The mass spectrometric data make it clear that field desorption tandem mass spectrometry can become a valuable additional technique for the structural analysis of anthracyclines.