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 13C 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 1H chemical shifts and 1H-detected NMR experiments for analyzing cell walls. Here we demonstrate 2D and 3D 1H-13C correlation experiments at both moderate and fast MAS frequencies of 10-50 kHz to resolve and assign 1H chemical shifts of matrix polysaccharides in Arabidopsis primary cell walls. Both 13C-detected and 1H-detected experiments are implemented and are shown to provide useful and complementary information. Using the assigned 1H chemical shifts, we measured long-range correlations between matrix polysaccharides and cellulose using 1H-1H instead of 13C-13C spin diffusion, and the 2D experiments can be conducted with either 13C or 1H detection.