Quantitative aspects in electrospray ionization ion trap and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry of malto-oligosaccharides

Analysis of carbohydrates and glycoconjugates by matrix-assisted laser desorption/ionization mass spectrometry: An update for 2011-2012

This review is the seventh update of the original article published in 1999 on the application of MALDI mass spectrometry to the analysis of carbohydrates and glycoconjugates and brings coverage of the literature to the end of 2012. General aspects such as theory of the MALDI process, matrices, derivatization, MALDI imaging, and fragmentation are covered in the first part of the review and applications to various structural types constitute the remainder. The main groups of compound are oligo- and poly-saccharides, glycoproteins, glycolipids, glycosides, and biopharmaceuticals. Much of this material is presented in tabular form. Also discussed are medical and industrial applications of the technique, studies of enzyme reactions, and applications to chemical synthesis. © 2015 Wiley Periodicals, Inc. Mass Spec Rev 36:255-422, 2017.

An automated mass spectrometry-based screening method for analysis of sulfated glycosaminoglycans

Glycosaminoglycans (GAGs) are linear polysaccharides, consisting of repeated disaccharide units, attached to core proteins in all multicellular organisms. Chondroitin sulfate (CS) and dermatan sulfate (DS) constitute a subgroup of sulfated GAGs for which the degree of sulfation varies between species and tissues. One major goal in GAG characterization is to correlate structure to function. A common approach is to exhaustively degrade the GAG chains and thereafter determine the amount of component disaccharide units. In large-scale studies, there is a need for high-throughput screening methods since existing methods are either very time- or samples consuming. Here, we present a new strategy applying MALDI-TOF MS in positive ion mode for semi-qualitative and quantitative analysis of CS/DS derived disaccharide units. Only a few picomoles of sample are required per analysis and 10 samples can be analyzed in 25 min, which makes this approach an attractive alternative to many established assay methods. The total CS/DS concentration in 19 samples derived from Caenorhabditis elegans and mammalian tissues and cells was determined. The obtained results were well in accordance with concentrations determined by a standard liquid chromatography-based method, demonstrating the applicability of the method for samples from various biological matrices containing CS/DS of different sulfation degrees.

Critical investigation of the substituent distribution in the polymer chains of hydroxypropyl methylcelluloses by (LC-)ESI-MS

Three hydroxypropyl methylcellulose samples (HPMC1-3, DS(Me) = 1.45, 1.29, and 1.36; MS(HP) = 0.28, 0.46, and 0.84) were analyzed with respect to their methyl and hydroxypropyl substitution pattern in the polymer chains. Ionization yield of HPMC oligomers in electrospray ionization ion trap mass spectrometry (ESI-IT-MS) is strongly influenced by the hydroxypropyl pattern. Therefore, a sample derivatization procedure, as well as suitable measurement conditions that enable relative quantification were elaborated. Analysis was performed by negative ESI-IT-MS after per(deutero)methylation, partial depolymerization, and reductive amination with m-aminobenzoic acid. Measurement parameters like solvent, trap drive, and voltages of the ion transportation unit were studied with regard to the suitability for quantitative evaluation. Using direct infusion of the samples, strong influence of trap drive and octopole settings was observed. Optimized measurement conditions were used for the determination of the HP pattern of the permethylated samples by direct infusion. The methyl pattern was determined from the perdeuteromethylated samples by high-performance liquid chromatography-electrospray tandem mass spectrometry. For HPMC1, substituents were both found to fit the random distribution model. The other two samples showed pronounced heterogeneity which could be interpreted in more detail by extracting methyl subpatterns depending on the number of HP groups.

Hydrolysis of wheat B-starch and characterisation of acetylated maltodextrin

Wheat B-starch was hydrolysed by α-amylase "Liquozyme supra" from Bacillus licheniformis at 90 °C and pH 7. After 2 h, the dextrose equivalent was 18; according to size exclusion chromatography, however, the hydrolysate contained not only dominant malto-oligosaccharides with the degree of polymerisation (DP)<10 but also more than 20% of components with DP higher than 40. The product was acetylated to a high degree as verified by FTIR and (1)H NMR (degree of substitution DS=3.1); nevertheless, detailed analysis of the MALDI-TOF mass spectra of the product showed that most of the malto-oligosaccharides molecules contained one or two residual hydroxyls. Size exclusion chromatography confirmed that the acetylated maltodextrin still contained a significant part with DP>40. This non-uniformity of acetylated maltodextrin, both with respect to DP and to DS, must be taken into account in the development of acetylated-maltodextrin applications such as use as plasticisers or compatibilisers in biodegradable composites.

Characterization of a new alginate lyase from newly isolated Flavobacterium sp. S20

Alginate lyase is a promising biocatalyst because of its application in saccharification of alginate for the production of biochemicals and renewable biofuels. This study described the isolation of a new alginate metabolizing bacterium, Flavobacterium sp. S20, from sludge samples and the characterization of its alginate lyase Alg2A. The alginate lyase gene, alg2A, was obtained by constructing and screening the genomic library of the strain S20 and overexpressed in Escherichia coli. Substrate specificity assays indicated Alg2A preferred poly-α-L-guluronate as a substrate over poly-β-D-mannuronate. In the saccharification process of a high content (10 %, w/v) of sodium alginate, the recombinant alginate lyase Alg2A yielded 152 of mM the reducing sugars after 69 h of reaction, and the amounts of oligosaccharides with a different degree of polymerization (DP) generated by Alg2A gradually accumulated without significant variation in the distribution of oligosaccharide compositions. These results indicated that Alg2A possessed high enzymatic capability for saccharifying the alginate, which could be used in saccharifying the alginate biomass prior to the main fermentation process for biofuels. In addition, Alg2A had a different endolytic reaction mode from both the two commercial alginate lyases and other alginate lyases from polysaccharide lyase family 7 owing to high yields of penta-, hex-, and hepta-saccharides in the hydrolysis products of Alg2A. Thus, Alg2A could be a good tool for the large-scale preparation of alginate oligosaccharides with high DP.