Professor Stephen Fry and colleagues at the University of Edinburgh have identified a plant enzyme with a unique function; it is the only enzyme known to act upon cellulose in a non-destructive way. The enzyme, hetero-trans-glucanase (HTG), was identified in horsetail plants (Equisetum), which are known for their single tall stalk with a curious ‘Lego-like’ architecture.
The unusual horsetail stalk was the trigger for Prof Fry’s research – to understand the biochemistry involved in making plant cell walls strong enough to form the tall and thin stalk. The research identified that the enzyme was unique to horsetails, and absent from all other plant types.
The HTG gene was cloned and characterised, and the enzyme was discovered to covalently link cellulose to different polysaccharide moieties within cell walls. The discovery has been patented and is now undergoing further proof of concept work. Importantly, HTG may be able to strengthen cellulose-based products by covalent crosslinking of bi-functional polysaccharides between cellulose molecules – both within and between cellulose fibres. This may lead to paper products that retain form and function when wet, or to stronger and more recyclable packaging. Similarly, the HTG enzyme can be used to permanently modify cellulose with dyes or other cargo to create new applications such as packaging with sensor or anti-microbial properties.
Prof Fry’s group is currently engaged in a proof-of-concept project to demonstrate strengthening and derivatization of cellulose products and is seeking commercial collaborators in the UK.