PI: Ulf Edlund
Co-PI: Mattias Hedenström

Staff: Tommy Öman, PhD student

Background

NMR spectroscopy is a well established method for structure determination of various organic molecules ranging from small molecules such as metabolites all the way up to large biomolecules such as proteins, DNA and polysaccharides. The chemical environment surrounding each atom as well their proximity to other atoms in a molecule can be studied with various experiments, enabling high-resolution 3D-structure determinations as well as verification of the chemical structure. NMR spectroscopy is well suited for wood characterization, both in solution and in the solid-state. Solid-state ¹³C CP/MAS NMR spectroscopy have been used extensively to investigate cellulose and lignin in pulp and wood in a non-invasive manner and can be used as a tool to detect morphological differences as well as the relative abundance of lignin and cellulose in wood of transgenic plants.

Detailed studies of biological samples in solution such as plant extracts and biofluids have historically been hampered by the inherent low sensitivity of NMR spectroscopy but recent technical advances such as stronger magnets and cryoprobes have enabled studies of these types of complex mixtures of compounds with a wide concentration span. Two- or even three-dimensional experiments of dissolved secondary cell walls will be used in an attempt to characterize the components of poplar wood. Spectral data from transgenic poplar can be used in conjunction with multivariate data analysis methods such as PCA and PLS in order determine the relationships between spectral properties and genotype.

Aim

Interesting poplar genotypes identified earlier within the FuncFiber project will be subjected to NMR studies with the aim of correlating genotype with chemical changes in the wood on a molecular level. The interpretation of observed spectral changes in wood from transgenic plants requires identification and assignment of as many as possible of the wood components. This can be accomplished with two-dimensional experiments such as HSQC, TOCSY and HSQC-TOCSY. Recently, a method for complete dissolution of secondary cell-walls (both lignin and polysaccharides) was developed in the laboratory of John Ralph, a FuncFiber collaborate. This method will be applied within the FuncFiber project with the aim of acquiring information-dense spectra suitable for multivariate data analysis.

Chemometric modelling such as PCA and PLS will be useful tools for the spectral analysis and robust protocols for sample preparation, acquisition and processing of NMR data will be developed to reduce irrelevant variation in the data. All NMR data will be deposited in a FuncFiber database together with data from other spectroscopic methods such as MS and FT-IR.