Pectins have a previously unsuspected role in holding plant cells together, according to recent research. Cell walls are made up of three major classes of polysaccharides: cellulose, hemicellulose and pectins. The molecular interactions of these polysaccharides walls were studied for the first time within intact plant cells using multidimensional solid state NMR, a technique related to magnetic resonance imaging (MRI). Scientists were able to look at the interactions of both rigid and mobile polysaccharides using solid state NMR by studying plants grown in a solution of water and sugar made with carbon-13 rather than the naturally abundant isotope carbon-12. This study showed that the ends of hemicellulose are deeply embedded into the cellulose microfibril, not just attached to its surface, and that pectin interacts with both the cellulose and the hemicellulose, joining them in a single network. The previously accepted model was based on a cellulose—hemicellulose framework embedded in an independent pectin matrix. This discovery demonstrates the power of combining carbon-13 labeling and solid state NMR to demystify plant cell wall structures in a nearly native environment. It may also help to elucidate how to modify plants cell walls to make it easier to turn plant material into biofuels.
Structure and Interactions of Plant Cell-Wall Polysaccharides by Two- and Three-Dimensional Magic-Angle-Spinning Solid-State NMR