Time-dependent viscometry study of endoglucanase action on xyloglucan: A real-time approach

•EGII decrease the apparent Mv, [η], Lp, Rg of XG immediately.•Viscometry could measure the degradation of XG by EGII forming oligosaccharides.•Galactose-containing sidechains on residues two positions away from the free C-6 glucose reducing end modulated EGII activity.•A complete hydrolysis of XG oligomers occurred after 24h. Hydrolysis of xyloglucan from Tamarindus indica and Hymenaea courbaril seeds with endoglucanase (EGII), which randomly breaks the (1→4)-linked β-glycosidic bonds of the polymer chain, was monitored in real time using time-dependent viscometry analysis (TDV). For both samples there was a decrease in the intrinsic viscosity ([η]), viscosity average molar mass (Mv), radius de gyration (Rg) and persistence length (Lp) immediately after the addition of the enzyme. It was observed the formation of oligosaccharides and oligomers composed of ∼2 units, up to 140min. Galactose-containing side chains two positions away from the non-substituted glucose, modulated the action of EGII, and the complete hydrolysis of the XG oligomers occurred after 24h. The results demonstrate for the first time the real-time degradation of xyloglucan as well the macromolecular and oligosaccharide composition during the EGII hydrolysis process.