Mechanistic basis of substrate–O <sub>2</sub> coupling within a chitin-active lytic polysaccharide monooxygenase: An integrated NMR/EPR study
Gastón Courtade, Luisa Ciano, Alessandro Paradisi, Peter J. Lindley, Zarah Forsberg, Morten Sørlie, Reinhard Wimmer, G.J. Davies, Vincent G. H. Eijsink, Paul H. Walton, Finn L. Aachmann
Abstract
Significance Lytic polysaccharide monooxygenases (LPMOs) have unique catalytic centers, at which a single copper catalyzes the oxidative cleavage of a glycosidic bond. The mechanism by which LPMOs activate molecular oxygen is key to understanding copper (bio)catalysis but remains poorly understood, largely because the insoluble and heterogeneous nature of LPMO substrates precludes the use of usual laboratory techniques. Using an integrated NMR/EPR approach, we have unraveled structural and electronic details of the interactions of an LPMO from Bacillus licheniformis and β-chitin. EPR spectroscopy on uniformly isotope 15 N-labeled 63 Cu(II)-LPMO provided insight into substrate-driven rearrangement of the copper coordination sphere that predisposes the enzyme for O 2 activation.