Xavier FALOURD - Characterization with NMR the interactions in macromolecular assemblies

Corinne Rondeau-Mouro and Marc Lahaye - UR BIA, INRAE Nantes

Interactions within macromolecular assemblies are at the origin of the multi-scale architecture (cells, tissues, organs) of plants as well as their functions and uses. The control of the qualities of use of plant products, the development of new formulated foods and the design of biosourced materials require in-depth knowledge of the physicochemical and rheological properties of the assemblies constituting these products.

These assemblies are composed mainly of cellulose, starch, hemicelluloses and/or pectins. It involve non-covalent inter- and/or intra-molecular interactions that are difficult to analyze in the natural environment and on small-scale ranges.

NMR has the advantage of being non-destructive, and can be used on a native sample, with little or no preparation. This advantage opens up a real opportunity to study the interactions between molecules of different nature while preserving the 3-dimensional structuring of the assemblies.

By modulating exogenous factors (hygrometry, temperature, pH, etc.), the interactions can be modified and thus some of them can be characterized. In addition, different NMR modalities are available (low field, high liquid and solid field) making it possible to characterize these assemblies on a large-scale range, from the molecule (nanometer) to the microns.

The main objective of my thesis is to demonstrate the contribution of NMR to characterize in detail interactions within complex polysaccharide assemblies. My work will have to propose validated measurement methods (via other complementary methods) on model systems and native assemblies, by trying to prioritize the contribution of interactions in these assemblies.