J. Hafrén, U. Westermark, H. Lennholm, N. Terashima
Formation of 13C-Enriched Cell-Wall DHP
Using Isolated Soft Xylem from Picea abies
Summary
Cell-wall dehydrogenation polymers (CW-DHP) were prepared by incubating a mixture of soft
xylem (differentiating xylem) from Picea abies, coniferin 13C-enriched at the side-chain ?-carbon
and unenriched coniferin, both with and without the addition of ?-glucosidase and glucose oxidase,
which causes an in situ polymerisation of the coniferyl alcohol in the cell wall. From difference
solid state 13C-NMR spectra between 13C-enriched CW-DHP and unenriched CW-DHP, the
bond frequencies involving specifically 13C-enriched carbon can be quantitatively determined. The
sub-structures in CW-DHP prepared without the addition of ?-glucosidase and glucose oxidase
showed more similarity to protolignin than CW-DHP prepared with the addition of extraneous
enzymes. The CW-DHP obtained without the addition of enzymes contained 36% ?-O-4-derived
sub-structures, 44% combined ?-?, ?-5 and ?-1 sub-structures and 20% coniferyl alcohol/coniferaldehyd
end groups. After acetone/water extraction of the CW-DHP, the content of ?-?, ?-5 and ?-1 structures decreased by 4%, and the ?-O-4 dominating peak increased by 4%. The 13C-enriched
CW-DHP material can be used to study lignin reactions in a solid wood matrix, and is also a powerful
system for detailed studies on in vivo lignification mechanisms and the effects on lignification
conditions on lignin structure.
Holzforschung, Walter de Gruyter
Print ISSN: 0018-3830
Volume: 56, 11/2002
Pages: 585 - 591
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