Conformational analysis of xylan chains

Mazeau, K.; Moine, Charlotte; Krausz, Pierre; Gloaguen, Vincent

doi:10.1016/j.carres.2005.09.023

Cited by 47 publications

(25 citation statements)

References 36 publications

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“…3). Previous modeling studies show that the preferred conformation for xylan in solution is a twisted 3 1 -fold helical screw conformation (Mazeau et al, 2005;Busse-Wicher et al, 2014), the same as was reported previously for the experimentally determined crystal structure of xylan hydrate (Nieduszynski and Marchessault, 1971). Free energy surfaces for the backbone glycosidic linkage conformations are presented in Figure 4 (for X 6 and XXA 3 XU m X) and Supplemental Figure S9 (for all other glycosidic linkages).…”

Section: Influence Of Regular Substitution Motifs On the Backbone Consupporting

confidence: 80%

Regular Motifs in Xylan Modulate Molecular Flexibility and Interactions with Cellulose Surfaces

et al. 2017

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ORCID IDs: 0000-0003-0277-2269 (J.B.); 0000-0001-6732-2571 (J.W.); 0000-0003-3572-7798 (F.V.).Xylan is tightly associated with cellulose and lignin in secondary plant cell walls, contributing to its rigidity and structural integrity in vascular plants. However, the molecular features and the nanoscale forces that control the interactions among cellulose microfibrils, hemicelluloses, and lignin are still not well understood. Here, we combine comprehensive mass spectrometric glycan sequencing and molecular dynamics simulations to elucidate the substitution pattern in softwood xylans and to investigate the effect of distinct intramolecular motifs on xylan conformation and on the interaction with cellulose surfaces in Norway spruce (Picea abies). We confirm the presence of motifs with evenly spaced glycosyl decorations on the xylan backbone, together with minor motifs with consecutive glucuronation. These domains are differently enriched in xylan fractions extracted by alkali and subcritical water, which indicates their preferential positioning in the secondary plant cell wall ultrastructure. The flexibility of the 3-fold screw conformation of xylan in solution is enhanced by the presence of arabinofuranosyl decorations. Additionally, molecular dynamic simulations suggest that the glycosyl substitutions in xylan are not only sterically tolerated by the cellulose surfaces but that they increase the affinity for cellulose and favor the stabilization of the 2-fold screw conformation. This effect is more significant for the hydrophobic surface compared with the hydrophilic ones, which demonstrates the importance of nonpolar driving forces on the structural integrity of secondary plant cell walls. These novel molecular insights contribute to an improved understanding of the supramolecular architecture of plant secondary cell walls and have fundamental implications for overcoming lignocellulose recalcitrance and for the design of advanced wood-based materials.

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Section: Influence Of Regular Substitution Motifs On the Backbone Consupporting

confidence: 80%

Regular Motifs in Xylan Modulate Molecular Flexibility and Interactions with Cellulose Surfaces

et al. 2017

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“…The heterogeneity of polymeric xylans confers a variety of unique characteristics on individual xylans [32]. Substituents, attached to the xylan backbone, generally act to limit the hydrolytic action of enzymes via steric interference.…”

Section: Discussionmentioning

confidence: 99%

Purification and characterisation of a xylanase from Thermomyces lanuginosus and its functional expression by Pichia pastoris

Gaffney

Carberry

Doyle

et al. 2009

Enzyme and Microbial Technology

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a b s t r a c tA xylanase produced by Thermomyces lanuginosus 195 by solid state fermentation (SSF) was purified 9.3-fold from a crude koji extract, with a 7.6% final yield. The purified xylanase (with an estimated mass of 22 kDa by SDS-PAGE) retained 18% relative activity when treated for 10 min at 100• C and approximately 90% relative activity when incubated at pH values ranging from 6 to 10. Xylanase activity in the purified preparation was significantly enhanced following treatment with manganese and potassium chlorides (p < 0.05) but significantly reduced by calcium, cobalt and iron (p < 0.05). The purified enzyme was also shown to be exclusively xylanolytic. The gene encoding xylanase activity from T. lanuginosus 195 was functionally expressed by Pichia pastoris. MALDI-ToF mass spectrometry and zymography were employed to confirm functional recombinant expression. Maximum xylanase titres were achieved following 120 h induction of the recombinant culture, yielding 26.8 U/mL. Achieving functional protein expression facilitates future efforts to optimise the cultivation conditions for heterologous xylanase production.

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“…[116][117][118] The different ordered conformation built from these low-energy conformers is shown in Figure 6. Molecular modeling of xylan chains predicts different low energy conformers for the b1 !…”

Section: Conformation Of Xylan Chainsmentioning

confidence: 99%

“…116 As a matter of fact, according to X-ray fiber diffraction studies, xylans are generally described as extended chains forming twisted ribbon-like strands, with threefold symmetry. 116 Lp's have been experimentally evaluated for AXs in solution. 4-linked polysaccharides such as cellulose and mannan chains, but actually the threefold screw symmetry of xylans differs quite largely from the twofold symmetry of cellulose and is not favorable for association with it.…”

Section: Conformation Of Xylan Chainsmentioning

confidence: 99%