Summary
The ultrastructure of holocellulose and alpha-cellulose from Pinus radiata D. Don was examined after treatment with cellulase for either 24 hours or 7 days. A procedure for localising the enzyme in situ using phosphotungstic acid is described. The pattern of degradation differed between the two substrates with alpha-cellulose being much more susceptible to hydrolysis than holocellulose. In both substrates the primary wall showed evidence of hydrolysis after 24 hours and was completely hydrolysed after 7 days. In holocellulose after 7 days treatment, hydrolysis of the secondary wall was confined to localised areas of the S3 layer sometimes penetrating into the S2 region. In contrast, alpha-cellulose showed uniform degradation across the secondary wall. Enzyme did not appear to penetrate the holocellulose but full penetration occurred in alpha-cellulose, the enzyme being closely associated with individual microfibrils. The reasons for these differences in degradation pattern are discussed.
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Donaldson, L.A. Ultrastructure of wood cellulose substrates during enzymatic hydrolysis. Wood Sci. Technol. 22, 33–41 (1988). https://doi.org/10.1007/BF00353226
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DOI: https://doi.org/10.1007/BF00353226