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Research article2025Peer reviewedOpen access

NMR spectroscopic studies of chitin oligomers - Resolution of individual residues and characterization of minor amide cis conformations

Wiesinger, Piera; Nestor, Gustav

Abstract

Chitin is the second most abundant biopolymer in nature after cellulose and is composed of N-acetylglucosamine (GlcNAc) connected via beta(1 -> 4)-glycosidic bonds. Despite its prominence in nature and diverse roles in pharmaceutical and food technological applications, there is still a need to develop methods to study structure and function of chitin and its corresponding oligomers. Efforts have been made to analyse chitin oligomers by NMR spectroscopy, but spectral overlap has prevented any differentiation between the interior residues. In this study, chitin oligomers up to hexaose with natural abundance of 15N were analysed with NMR spectroscopy in aqueous solution. Different 1H,15N-HSQC pulse sequences were evaluated to obtain the best resolution and sensitivity. Interior residues were resolved in the 15N dimension and detailed chemical shifts of amide proton and nitrogen are reported for the first time. Additionally, all oligomers were analysed for the presence of the amide cis form and its corresponding chemical shifts were assigned. This study exploits the information that can be obtained from chitin oligomers with NMR spectroscopy and depicts methods for detailed analysis of glycans containing oligomers of N-acetylglucosamine.

Keywords

Chitin oligomers; N-Acetylglucosamine; (GlcNAc)2-6; NMR spectroscopy; 1H,15N-HSQC; Amide proton; cis/trans isomerisation

Published in

Carbohydrate Polymers
2025, volume: 351, article number: 123122
Publisher: ELSEVIER SCI LTD

SLU Authors

UKÄ Subject classification

Polymer Chemistry

Publication identifier

  • DOI: https://doi.org/10.1016/j.carbpol.2024.123122

Permanent link to this page (URI)

https://res.slu.se/id/publ/140117