2D-NMR (HSQC) difference spectra between specifically C-13-enriched and unenriched protolignin of Ginkgo biloba obtained in the solution state of whole cell wall material
Journal article, 2009

In the structural analysis of lignins by C-13-NMR, signal overlap limits definitive assignment and accurate intensity measurement. Selective labeling by C-13-enrichment of a specific carbon in lignin enhances its signal intensity in the spectrum. Further enhancement of the specifically labeled carbons can be realized via difference spectra created from the enriched and unenriched samples. Difference 2D C-13-H-1 correlation (HSQC) NMR spectra, derived from the spectra of specifically C-13-enriched lignin model polymers (so-called dehydrogenation polymers) and their unenriched counterparts, take advantage of the enhanced dispersion afforded by both C-13 and H-1 chemical shifts, diminishing the difficulties arising from the signal-overlap problem and aiding in definitive signal assignments. In this research, protolignin in xylem cell walls was specifically C-13-enriched at all of the individual phenylpropanoid side-chain carbons by feeding C-13-enriched coniferins to growing stems of Ginkgo biloba. The whole xylem fractions containing C-13-enriched and unenriched protolignins were dissolved in a mixture of N-methylimidazole and DMSO, and then acetylated. Solution state 2D-NMR (HSQC) spectra of the acetylated whole cell wall were acquired. Difference spectra between the walls containing C-13-enriched and unenriched lignins afforded simplified 2D spectra in which well-separated signals were assigned exclusively to the specifically enriched carbons. This novel NMR technique provides a useful tool for elucidation of entire protolignin in the cell wall of ginkgo xylem.


part 1



side-chain carbons




2D-difference NMR spectroscopy

lignin biosynthesis


polymer (DHP)

carbon-13 enrichment




carbon-13-NMR spectroscopy


N. Terashima

T. Akiyama

USDA ARS U.S. Dairy Forage Research Center

S. Ralph

USDA Forest Products Laboratory

D. Evtuguin

Centro de Investigacao em Materiais Ceramicos e Compositos

C. P. Neto

Centro de Investigacao em Materiais Ceramicos e Compositos

Jim Parkås

Chalmers, Chemical and Biological Engineering, Forest Products and Chemical Engineering

Magnus Paulsson

Chalmers, Chemical and Biological Engineering, Forest Products and Chemical Engineering

U. Westermark

Luleå University of Technology

J. Ralph

University of Wisconsin Madison


0018-3830 (ISSN) 1437-434X (eISSN)

Vol. 63 4 379-384

Subject Categories

Other Engineering and Technologies not elsewhere specified



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