Distinct Interaction of Lytic Polysaccharide Monooxygenase with Cellulose Revealed by Computational and Biochemical Studies.

A distinct interaction pattern of lytic polysaccharide monooxygenases (LPMOs) with their insoluble substrate, cellulose, was revealed through the combination of computational and biochemical approaches. The results indicated that the enzymes can stably bind on the flat hydrophobic surface of cellulose via the interactions of the key residues located in the axis across the conserved distal tyrosine residue and copper ion with two adjacent cellulose chains. Further studies on the correlation of substrate binding and H2O2 accumulation suggested that LPMOs involved in the productive binding on the insoluble polysaccharides not only fail to accumulate H2O2 but also consume the H2O2 produced by the unbound molecules under the lab condition. This was further substantiated by quantum-mechanical calculations. These findings broadened our knowledge of the interaction between enzymes and insoluble substrates and deepened our understanding of the role that H2O2 plays in LPMO activity.