Molecular organization in the native state of woody tissue: Studies of tertiary structure using the Raman microprobe solid state 13C NMR and biomimetic tertiary aggregates. Progress report, July 1, 1989--June 30, 1993

摘要

We have previously shown that all relatively pure plant and bacterial celluloses are, in their native states, composites of two lattice forms, I(sub (alpha)) and I(sub (beta)), and that the two forms possess molecular chains in the same conformations but with different hydrogen bonding patterns. In the current period we have demonstrated that in higher plant cell wall matrices, the hemicelluloses are likely to have a regulatory function during the aggregation of cellulose. Different hemicelluloses appear to influence the aggregation in different ways. We have also developed preliminary evidence indicating the hemicelluloses may have a protective function against the action of some cellulolytic enzymes. The specific accomplishments during the current period are detailed. Demonstration that hemicelluloses present during biogenesis can transform bacterial cellulose into a cellulose typical of higher plant celluloses, and that each hemicellulose has a different effect on the pattern of aggregation. Evidence is presented that the hemicelluloses may limit the action of certain cellulolytic enzymes, suggesting that their function may go beyond regulation to include passive resistance to cellulolytic pathogens. Enhancing the potential of the Raman microprobe technique for mapping variability of lignin in the cell wall by identifying the contribution of the different substructures of lignin to the intensity of the key band in the Raman spectrum of lignin. Mapping of the variability of lignin across two cell wall sections. The mappings have convoluted within them both composition and concentration, but they demonstrate the potential of the method and point to the improvements we are now making so as to distinguish between variability of concentration and variability of composition.