Direct Determination of Hydroxymethyl Conformations of Plant Cell Wall Cellulose Using <sup>1</sup>H Polarization Transfer Solid-State NMR [electronic resource]

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Tác giả:

Ngôn ngữ: eng

Ký hiệu phân loại: 547.7 Macromolecules and related compounds

Thông tin xuất bản: Washington, D.C. : Oak Ridge, Tenn. : United States. Dept. of Energy. Office of Science ; Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy, 2018

Mô tả vật lý: Size: p. 1485-1497 : , digital, PDF file.

Bộ sưu tập: Metadata

ID: 263032

 In contrast to the well-studied crystalline cellulose of microbial and animal origins, cellulose in plant cell walls is disordered due to its interactions with matrix polysaccharides. Plant cell wall (PCW) is an undisputed source of sustainable global energy
  therefore, it is important to determine the molecular structure of PCW cellulose. The most reactive component of cellulose is the exocyclic hydroxymethyl group: when it adopts the tg conformation, it stabilizes intrachain and interchain hydrogen bonding, while gt and gg conformations destabilize the hydrogen-bonding network. So far, information about the hydroxymethyl conformation in cellulose has been exclusively obtained from <
 sup>
 13<
 /sup>
 C chemical shifts of monosaccharides and oligosaccharides, which do not reflect the environment of cellulose in plant cell walls. Here, we use solid-state Nuclear Magnetic Resonance (ssNMR) spectroscopy to measure the hydroxymethyl torsion angle of cellulose in two model plants, by detecting distance-dependent polarization transfer between H4 and H6 protons in 2D <
 sup>
 13<
 /sup>
 C?<
 sup>
 13<
 /sup>
 C correlation spectra. We show that the interior crystalline portion of cellulose microfibrils in Brachypodium and Arabidopsis cell walls exhibits H4?H6 polarization transfer curves that are indicative of a tg conformation, whereas surface cellulose chains exhibit slower H4?H6 polarization transfer that is best fit to the gt conformation. Joint constraints by the H4?H6 polarization transfer curves and <
 sup>
 13<
 /sup>
 C chemical shifts indicate that it is unlikely for interior cellulose to have a significant population of the gt and gg conformation mixed with the tg conformation, while surface cellulose may adopt a small percentage of the gg conformation. These results provide new constraints to the structure and matrix interactions of cellulose in plant cell walls, and represent the first direct determination of a torsion angle in an important noncrystalline carbohydrate polymer.
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