title: Evaluating endoglucanase Cel7B-lignin interaction mechanisms and kinetics using quartz crystal microgravimetry.
abstract: The kinetics and mechanisms of protein interactions with solid surfaces are important to fields as diverse as industrial biocatalysis, biomedical engineering, food science, and cell biology. The nonproductive adsorption of cellulase enzymes to lignin, a plant cell wall polymer, reduces their effectiveness in saccharifying biomass. Cellulase has been shown to interact with lignin, but the heterogeneity of lignin surfaces, challenges in measuring irreversible components of these interactions, and fast adsorption rates make quantifying the reaction kinetics difficult. This work employs quartz crystal microgravimetry with dissipation monitoring (QCM-D) for real-time measurement of adsorbed mass on a flat lignin surface. We have developed a method for casting homogeneous lignin films that are chemically similar to lignin found in pretreated biomass, and used QCM-D to compare three models of reversible-irreversible binding behavior: a single-site transition model, a transition model with changing adsorbate footprint, and a two-site transition model. Of the three models tested, the two-site transition model provides the only kinetic mechanism able to describe the behavior of Cel7B binding to lignin. While the direct implications of lignin-cellulase interactions may be limited to biomass deconstruction for renewable energy and green chemistry, the analytical and experimental methods demonstrated in this work are relevant to any system in which the kinetics and reaction mechanism of reversible and irreversible protein adsorption at a solid-liquid interface are important.
authors.affiliation: Department of Chemical and Biomolecular Engineering, University of California, Berkeley, California 94720.|Energy Biosciences Institute, University of California, Berkeley, California 94720.
authors.forename: Katherine A
authors.initials: KA
authors.lastname: Pfeiffer
authors.affiliation: Energy Biosciences Institute, University of California, Berkeley, California 94720.
authors.forename: Hagit
authors.initials: H
authors.lastname: Sorek
authors.affiliation: Department of Chemical and Biomolecular Engineering, University of California, Berkeley, California 94720.|Energy Biosciences Institute, University of California, Berkeley, California 94720.
authors.forename: Christine M
authors.initials: CM
authors.lastname: Roche
authors.affiliation: Department of Chemical and Biomolecular Engineering, University of California, Berkeley, California 94720.|Energy Biosciences Institute, University of California, Berkeley, California 94720.
authors.forename: Kathryn L
authors.initials: KL
authors.lastname: Strobel
authors.affiliation: Department of Chemical and Biomolecular Engineering, University of California, Berkeley, California 94720.|Energy Biosciences Institute, University of California, Berkeley, California 94720.
authors.forename: Harvey W
authors.initials: HW
authors.lastname: Blanch
authors.affiliation: Department of Chemical and Biomolecular Engineering, University of California, Berkeley, California 94720. clark@berkeley.edu.|Energy Biosciences Institute, University of California, Berkeley, California 94720. clark@berkeley.edu.
authors.forename: Douglas S
authors.initials: DS
authors.lastname: Clark
mesh_terms: D002480:Cellulase / Q000378:metabolism*; D002621:Chemistry / Q000379:methods*; D007700:Kinetics; D008031:Lignin / Q000378:metabolism*; D011485:Protein Binding
chemical_list: D008031:Lignin; D002480:Cellulase
keywords: cellulase; kinetic modeling; lignin; nonspecific adsorption; quartz crystal gravimetry; surface kinetics