Soft Matter Physics Seminar: Professor Stephen C Fry, University of Edinburgh

Professor Stephen C Fry, of the Edinburgh Cell Wall Group, University of Edinburgh, will be presenting a seminar on his research.

Title: Probing the accessibility of fibril-associated cellulose to the surrounding aqueous solution

Cellulose, the most abundant organic substance on earth, occurs in plant cell walls in the form of microfibrils, within which the linear cellulose molecules lie anti-parallel and in a semi-crystalline arrangement. In this form, cellulose [-(14)-D-glucan] is water-insoluble and highly intractable, being difficult to digest by hydrolytic enzymes. It is assumed that molecules near the centre of a microfibril are inaccessible to the surrounding aqueous environment, whereas at least some of the peripheral molecules are accessible. It would be biotechnologically valuable to be able to functionalise cellulose, a goal dependent on molecular ‘accessibility’.

We are exploring how different preps of cellulose differ in accessibility, using three main approaches: (1) We have discovered a novel enzyme, hetero-trans--glucanase (HTG), which can form covalent bonds between cellulose and a second plant polysaccharide (xyloglucan).1 The discovery and possible biological roles of HTG will be discussed, as will its ability to discriminate between accessible and inaccessible cellulose molecules. (2) The ability of the tritium of radioactive water (3H2O) to become attached to O atoms of cellulose, forming –O3H groups, also probes their accessibility. (3) The ability of radioactively labelled, short, water-soluble fragments of cellulose (e.g. [3H]cellopentaitol), to adsorb to cellulosic surfaces via hydrogen-bonding is a third way of probing accessibility.

The results are revealing considerable variation in the surface accessibility of different cellulose preps, and thus in their biotechnological potential. Reference 1 T.J. Simmons, K.E. Mohler, C. Holland, F. Goubet, L. Franková, D.R. Houston, A.D. Hudson, F. Meulewaeter, S.C. Fry (2015) Hetero-trans--glucanase, an enzyme unique to Equisetum plants, functionalises cellulose. Plant Journal, 83, 753–769.

All are welcome to attend. For further information please contact Dr Mike Ries.