UK researchers find key to breaking down cellulose

In the UK, molecules 10,000 times narrower than the width of a human hair could hold the key to making possible wooden skyscrapers and more energy-efficient paper production, according to research published in the journal Nature Communications. The study, led by a father and son team at the Universities of Warwick and Cambridge, solves a long-standing mystery of how key sugars in cells bind to form strong, indigestible materials.

“We knew the answer must be elegant and simple,” explains Professor Paul Dupree from the Department of Biochemistry at the University of Cambridge, who led the research. “And in fact, it was. What we found was that cellulose induces xylan to untwist itself and straighten out, allowing it to attach itself to the cellulose molecule. It then acts as a kind of ‘glue’ that can protect cellulose or bind the molecules together, making very strong structures.”

The finding was made possible due to an unexpected discovery several years ago in Arabidopsis, a small flowering plant related to cabbage and mustard. Professor Dupree and colleagues showed that the decorations on xylan can only occur on alternate sugar molecules within the polymer – in effect meaning that the decorations only appear on one side of xylan. This led the team of researchers to survey other plants in the Cambridge University Botanic Garden and discover that the phenomenon appears to occur in all plants, meaning it must have evolved in ancient times, and must be important.

To explore this in more detail, they turned to an imaging technique known as solid state nuclear magnetic resonance (ssNMR), which is based on the same physics as hospital MRI scanners, but can reveal structure at the nanoscale. However, while ssNMR can image carbon, it requires a particular heavy isotope of carbon, carbon-13. This meant that the team had to grow their plants in an atmosphere enriched with a special form of carbon dioxide – carbon-13 dioxide.

Understanding how cellulose and xylan fit together could have a dramatic effect on industries as diverse as biofuels, paper production and agriculture, according to Paul Dupree.