High-resolution solution-state NMR of unfractionated plant cell walls

Abstract

Detailed structural studies on the plant cell wall have traditionally been difficult. NMR is one of the preeminent structural tools, but obtaining high-resolution solution-state spectra has typically required fractionation and isolation of components of interest. With recent methods for dissolution of, admittedly, finely divided plant cell wall material, the wall can now be studied by solution-state NMR. Exploiting the dispersion of 2D (and even 3D) NMR allows strikingly detailed structural analysis of the wall components without the need for isolation and fractionation. The initial method utilized acetylation of the wall to prepare optimal samples for NMR, but more recently we avoid the acetylation step; spectra from unacetylated walls have improved resolution of some components and allow natural acetylation (of polysaccharides and lignins) to be readily identified. The structural “fingerprint” of the cell wall produced by 2D ¹³C–¹H correlative NMR experiments is potentially unmatched by any other spectroscopy. Dissolution/NMR methods therefore potentially lend themselves well to chemometrics methods once the issues of dealing with multivariate analyses on 2D NMR data have been addressed. Improved throughput (in principle, toward 50 samples per day) seems possible.

Citation

Ralph, John; Lu, Fachuang; Kim, Hoon; Ress, Dino; Yelle, Daniel J.; Hammel, Kenneth E.; Ralph, Sally A.; Nanayakkara, Bernadette; Wagner, Armin; Akiyama, Takuya; Schatz, Paul F.; Mansfield, Shawn D.; Terashima, Noritsugu; Boerjan, Wout; Sundberg, Bjorn; Hedenstrom, Mattias. 2009. High-resolution solution-state NMR of unfractionated plant cell walls. In: Proceedings of the 15th International Symposium on Wood, Fiber and Pulping Chemistry, 2009 June 15-18, Oslo, Norway. (P-105) Oslo, Norway: Congress-Conference AS, 2009: [4] p.