Spatial relationships between polymers in Sitka spruce: proton spin-diffusion studies

Altaner, C., Apperley, D.C. and Jarvis, M.C. (2006) Spatial relationships between polymers in Sitka spruce: proton spin-diffusion studies. Holzforschung, 60(6), pp. 665-673. (doi:10.1515/HF.2006.112)

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Publisher's URL: http://dx.doi.org/10.1515/HF.2006.112

Abstract

The spatial arrangement of polymers in Sitka spruce (Picea sitchensis) was investigated by NMR proton spin-diffusion studies, supplemented by deuterium-exchange experiments monitored by FTIR spectroscopy. The FTIR spectra of earlywood sections after vapour-phase exchange with deuterium oxide showed that 43% of the hydroxyl groups were accessible to deuteration. This value is lower than predicted in the absence of aggregation of cellulose microfibrils into larger units, but greater than the predicted level of deuteration if 3.5-nm microfibrils surrounded by hemicellulose sheaths were aggregated into 4×4 arrays without space for deuterium oxide to penetrate between the microfibrils. The rate of proton spin diffusion between lignin and cellulose was consistent with the presence of microfibril arrays with approximately these dimensions and with lignin located outside them, in both earlywood and latewood. Proton spin-diffusion data for hemicelluloses were complicated by difficulties in assigning signals to glucomannans and xylans, but there was evidence for the spatial association of one group of hemicelluloses, including acetylated glucomannans, with cellulose surfaces, while another group of hemicelluloses was in spatial proximity to lignin. These data are consistent with a number of nanoscale models for the Sitka spruce cell wall, including a model in which glucomannans are associated with microfibril surfaces within the aggregate and water can penetrate partially between these surfaces, and one in which all non-cellulosic polymers and water are excluded from the interior of each microfibril aggregate.

Item Type:Articles
Keywords:cell wall models, cellulose, hemicellulose, lignin, NMR spectroscopy, supramolecular structure of wood
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Altaner, Dr Clemens and Jarvis, Dr Michael
Authors: Altaner, C., Apperley, D.C., and Jarvis, M.C.
Subjects:Q Science > QK Botany
Q Science > QD Chemistry
Q Science > QH Natural history > QH345 Biochemistry
College/School:College of Science and Engineering > School of Chemistry
University Centres > Glasgow Materials Research Initiative
Journal Name:Holzforschung
Publisher:Walter de Gruyter
ISSN:0018-3830
Copyright Holders:Copyright © 2006 Walter de Gruyter
First Published:First published in Holzforschung 60(6):665-673
Publisher Policy:Reproduced in accordance with the copyright policy of the publisher

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