Binding Interactions of Enzymatically Modified Plant Cell Wall Polymers Monitored by QCM-D

The enzyme-plant-cell-wall degradation complex is wrought with binding interactions that both advance and provide resistance to the end-goals of many 2nd generation bioconversion processes. Of key importance is the productive and non-productive binding of cell-wall degrading enzymes to target and non-target substrates, but also binding interactions and junction zone formation between like and unlike plant cell-wall polymers. In previous work we have hypothesized that the likelihood different cell-wall polymers engage in such binding interactions is in large part related to the degree per unit mass that polymers constrain water creating what we believe are varied states of lower entropy water associating with them. In this work via low-field NMR and traditional enzyme assays we have shown that polymers that more greatly constrained water in a system were more likely to be inhibitory to cellulases saccharifying cellulose. Furthermore, quartz crystal microbalance with dissipation (QCM-D) study showed the most constraining, most inhibitory, polymers formed the most rigid layers when interacting with cellulose; suggesting a better understanding of water-polymer interactions may help alleviate some inhibitory bottlenecks associated with enzymatic lignocellulose conversion. In this current work we have expanded upon this to investigate how enzymatic modifications to plant cell wall polymers that have the potential to alter water-polymer association effect binding interactions. We will present two cases; (1) the enzymatic debranching of wheat arabinoxylan and it effect on binding interactions with cellulose and (2) the enzymatic oxidation of the cellulose surface and the effect on the binding of processive cellulase cel7A.