Fast MAS 1H-13C correlation NMR for structural investigations of plant cell walls

Plant cell walls consist of a mixture of polysaccharides that render the cell wall a strong and dynamic material. Understanding the molecular structure and dynamics of wall polysaccharides is important for understanding and improving the properties of this energy-rich biomaterial. So far, solid-state NMR studies of cell wall structure and dynamics have solely relied on C-13 chemical shifts measured from 2D and 3D correlation experiments. To increase the spectral resolution, sensitivity and upper limit of measurable distances, it is of interest to explore H-1 chemical shifts and H-1-detected NMR experiments for analyzing cell walls. Here we demonstrate 2D and 3D H-1-C-13 correlation experiments at both moderate and fast MAS frequencies of 10-50 kHz to resolve and assign H-1 chemical shifts of matrix polysaccharides in Arabidopsis primary cell walls. Both C-13-detected and H-1-detected experiments are implemented and are shown to provide useful and complementary information. Using the assigned H-1 chemical shifts, we measured long-range correlations between matrix polysaccharides and cellulose using H-1-H-1 instead of C-13-C-13 spin diffusion, and the 2D experiments can be conducted with either C-13 or H-1 detection.