Enzymatic synthesis of cellulose II-like substance via cellulolytic enzyme-mediated transglycosylation in an aqueous medium

The enzymatic synthesis of cellulose-like substance via a non-biosynthetic pathway has been achieved by transglycosylation in an aqueous system of the corresponding substrate, cellotriose for cellulolytic enzyme endo-acting endoglucanase I (EG I) from Hypocrea jecorina. A significant amount of water-insoluble product precipitated out from the reaction system. MALDI-TOF mass analysis showed that the resulting precipitate had a degree of polymerization (DP) of up to 16 from cellotriose. Solid-state 13C NMR spectrum of the resulting water-insoluble product revealed that all carbon resonance lines were assigned to two kinds of anhydroglucose residues in the corresponding structure of cellulose II. X-ray diffraction (XRD) measurement as well as 13C NMR analysis showed that the crystal structure corresponds to cellulose II with a high degree of crystallinity. We propose the multiple oligomers form highly crystalline cellulose II as a result of self-assembly via oligomer–oligomer interaction when they precipitate.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► The enzymatic synthesis of cellulose II-like substance was achieved. ► The synthesis was performed using cellotriose and cellulase in an aqueous medium. ► A significant amount of water-insoluble product precipitated out from the reaction system. ► MALDI-TOF mass and solid-state 13C NMR analysis showed a cellulose II structure. ► XRD measurement showed that the crystal structure corresponds to cellulose II.