A new study, led by a father and son team at the University of Warwick and University of Cambridge, has solved the mystery of how key sugars in plant cells bind to form strong structural materials. Scientists have known for some time that two polymers in the cell walls of materials such as wood, xylan, and cellulose must somehow interact and stick together to form the strong walls, but did not know how this occured until now.
Published in the journal, Nature Communications, this new research explains how the long and winding carbon chain, xylan, with its so-called ‘decorations’ of other sugars and molecules attached, adheres so strongly to thick, rod-like cellulose molecules.
“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 structure of the xylan-cellulose bonds was examined using an imaging technique known as solid state nuclear magnetic resonance (ssNMR), which works similarly to hospital MRI scanners, just at a nanoscale. This was carried out by Paul Dupree’s father and co-author on the paper, Professor Ray Dupree, at the University of Warwick, to allow them to see, for the first time ever, how the two polymers slot together.
“One of the biggest barriers to ‘digesting’ plants – whether that’s for use as biofuels or as animal feed, for example – has been breaking down the tough cellular walls,” said Paul Dupree. “Take paper production – enormous amounts of energy are required for this process. A better understanding of the relationship between cellulose and xylan could help us vastly reduce the amount of energy required for such processes.”
Along with allowing the breakdown of matter to be more efficient, this discovery could also pave the way to more sustainable wooden buildings. According to the University of Cambridge, there are already plans in place to use stronger wood in new houses in the UK, and Paul Dupree is involved in an initiative that is exploring the possibility of using modified wood to build skyscrapers.