title: Xylan as limiting factor in enzymatic hydrolysis of nanocellulose.
abstract: The role of xylan as a limiting factor in the enzymatic hydrolysis of cellulose was studied by hydrolysing nanocellulose samples prepared by mechanical fibrillation of birch pulp with varying xylan content. Analyzing the nanocelluloses and their hydrolysis residues with dynamic FT-IR spectroscopy revealed that a certain fraction of xylan remained tightly attached to cellulose fibrils despite partial hydrolysis of xylan with xylanase prior to pulp fibrillation and that this fraction remained in the structure during the hydrolysis of nanocellulose with cellulase mixture as well. Thus, a loosely bound fraction of xylan was predicted to have been more likely removed by purified xylanase. The presence of loosely bound xylan seemed to limit the hydrolysis of crystalline cellulose, indicated by an increase in cellulose crystallinity and by preserved crystal width measured with wide-angle X-ray scattering. Removing loosely bound xylan led to a proportional hydrolysis of xylan and cellulose with the cellulase mixture.
authors.affiliation: University of Helsinki, Department of Physics, P.O. Box 64, FI-00014 Helsinki, Finland. paavo.a.penttila@helsinki.fi
authors.forename: Paavo A
authors.initials: PA
authors.lastname: Penttilä
authors.forename: Anikó
authors.initials: A
authors.lastname: Várnai
authors.forename: Jaakko
authors.initials: J
authors.lastname: Pere
authors.forename: Tekla
authors.initials: T
authors.lastname: Tammelin
authors.forename: Lennart
authors.initials: L
authors.lastname: Salmén
authors.forename: Matti
authors.initials: M
authors.lastname: Siika-aho
authors.forename: Liisa
authors.initials: L
authors.lastname: Viikari
authors.forename: Ritva
authors.initials: R
authors.lastname: Serimaa
mesh_terms: D002480:Cellulase / Q000737:chemistry*; D002482:Cellulose / Q000737:chemistry*; D004789:Enzyme Activation; D006868:Hydrolysis; D053758:Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure*; D010316:Particle Size; D011485:Protein Binding; D014990:Xylans / Q000737:chemistry*
chemical_list: D014990:Xylans; D002482:Cellulose; D002480:Cellulase