Inhibition of Holocellulose Active Enzymes due to Steric Hindrances and Non-specific Binding on Lignocellulose Surfaces

The adsorption of xylanases from Thermobifida fusca (TfuXyn10B and TfuXyn11A) onto lignin samples derived from kraft and organosolv pulping processes was monitored using a quartz crystal microbalance with dissipation (QCM-D). While TfuXyn11A comprises a C-terminal family 2b carbohydrate-binding module (CBM) and bound to lignin surfaces, TfuXyn10B lacking a CBM did not bind any lignin source. Pretreatment with bovine serum albumin effectively prevented TfuXyn11A adsorption. Enzyme adsorption was limited to a surface interaction and did not lead to swelling of the lignin coating. A novel approach was developed to distinguish between the mass of protein and protein-bound water binding to the lignin surfaces. Kinetic analysis of enzyme association and dissociation revealed that kinetics driving desorption of TfuXyn11A from each lignin source were similar. By contrast, the adsorption kinetics was highest for TfuXyn11A binding to kraft lignin. A lignocellulose composite surface composed of lignin, cellulose and xylan was developed to study impedance of cellulase actionM.A.S