Optimizing acid hydrolysis for monosaccharide compositional analysis of Nostoc cf. linckia acidic exopolysaccharide

The exact estimation of monosaccharide composition is important in the primary structure elucidation of polysaccharides. An acid hydrolysis is usually performed for glycosidic bonds cleavage and releasing of monosaccharides. In this study, optimal conditions of total acid hydrolysis using trifluoroa...

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Bibliographic Details
Published in:Carbohydrate research 2021-10, Vol.508, p.108400, Article 108400
Main Authors: Uhliariková, Iveta, Matulová, Mária, Capek, Peter
Format: Article
Language:English
Subjects:
1H NMR spectroscopy
Acid hydrolysis
Acidic exopolysaccharide
Hydrolysis
Monosaccharide composition
Monosaccharides
Uronic Acids
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Summary:The exact estimation of monosaccharide composition is important in the primary structure elucidation of polysaccharides. An acid hydrolysis is usually performed for glycosidic bonds cleavage and releasing of monosaccharides. In this study, optimal conditions of total acid hydrolysis using trifluoroacetic acid (TFA) of acidic lactylated Nostoc cf. linckia exopolysaccharide (EPS) were investigated by NMR spectroscopy. Results of a series of experiments with modified acid concentration, temperature and time of hydrolysis, have shown 2 M TFA, 110 °C, 3 h as the most optimal. The stability of EPS monosaccharide components was also explored. Low stability was found at all tested conditions already during the first hour of hydrolysis; all neutral monosaccharides were degraded from 25% to 40% and glucuronic acid to 75%. NMR, contrary to standard techniques used in monosaccharide compositional analysis (HPLC, HPAEC), allowed simultaneous quantification of all GlcA forms; the free one, that one linked in oligosaccharides, as well as GlcA degradation product γ-lactone. NMR as detection method improves information about uronic acid content in EPS. [Display omitted] •Fast degradation of free GlcA to γ-lactone and non saccharidic compounds.•Low and different stabilities of neutral sugars.•1H NMR quantification of GlcA and its derivatives in cyclic forms in hydrolysates.•Optimal EPS hydrolysis conditions led the lowest sugar degradation.•Sugar compositional analysis using 1H NMR affords the most precise data.
ISSN:0008-6215
1873-426X
1873-426X
DOI:10.1016/j.carres.2021.108400