Solid-State 13C NMR Study of a Composite of Tobacco Xyloglucan and Gluconacetobacter xylinus Cellulose: Molecular Interactions between the Component Polysaccharides

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• 作者：Tracey J. Bootten ; Philip J. Harris ; Laurence D. Melton ; Roger H. Newman
• 刊名：Biomacromolecules
• 出版年：2009
• 出版时间：November 9, 2009
• 年：2009
• 卷：10
• 期：11
• 页码：2961-2967
• 全文大小：194K
• 年卷期：v.10,no.11(November 9, 2009)
• ISSN：1526-4602

文摘

To investigate possible molecular interactions between xyloglucans (XGs) and cellulose in plant cell walls, a model composite was produced using cellulose from the bacterium Gluconacetobacter xylinus and XG from the walls of a tobacco cell-suspension culture that had been incubated with ¹³C-labeled glucose. Solid-state ¹³C NMR with cross-polarization (CP) and magic-angle spinning (MAS) was used in combination with proton spin-relaxation editing to separate signals from crystalline (rigid) and less rigid domains of the composite. Signals from XG were confined to subspectra of less rigid domains, with no detectable signals from XG attached to surfaces of cellulose crystallites. Signal displacements indicated XGs were more rigid than the mobile coil (twisted backbone) conformation expected for unattached XGs. Similar ¹³C chemical shifts were observed in a single-pulse excitation experiment. The results were not compatible with extensive hydrogen bonding between XG and cellulose, but were consistent with a composite structure in which cellulose crystallites were embedded in a matrix of XG with a semirigid (straightened backbone) conformation, that is, a matrix that is partly ordered rather than amorphous.