1.14.99.54 1.2 A resolution X-ray diffraction data, room-temperature neutron diffraction data to 2.12 A resolution 739826 1.14.99.54 C-terminally truncated variant containing 21 residues of the predicted linker domain, to 0.95 A resolution. The linker forms an integral part of the catalytic domain structure, covering a hydrophobic patch on the catalytic AA9 module. The oxidized catalytic center contains a Cu(II) coordinated by two His ligands, one of which has a His-brace in which the His-1 terminal amine group also coordinates to a copper. The final equatorial position of the Cu(II) is occupied by a water-derived ligand 745374 1.14.99.54 comparative analysis of sequences, solved structures, and homology models from AA9 and AA10 LPMO families.The two LPMO families are highly conserved, structurally they have minimal sequence similarity outside the active site residues 740205 1.14.99.54 comparison of isoforms LPMO9A, LPMO9B and LPMO9C. LPMO9B contains distal from the coordinated copper sphere an additional loop (Gly115-Asn121), which is not present in LPMO9A and LPMO9C. The copper ion in LPMO9A, LPMO9B and LPMO9C is coordinated by His1-His68-Tyr153, His1-His79-Tyr170 and His1-His84-Tyr166, respectively. All three LPMOs share two putative disulfide bridges 740210 1.14.99.54 comparison of isoforms PMO-2 and PMO-3 at 1.1 and 1.37 resolution, respectively. In the structures, dioxygen species are found in the active sites. The enzyme substrate-binding surfaces contain highly varied aromatic amino acid and glycosylation positions 741445 1.14.99.54 crystals obtained in the presence of high zinc-ion concentrations are used. A structure with an ordered zinc-bound active site at 1.65 A resolution, and three structures from crystals soaked with maltooligosaccharides in solutions devoid of zinc ions are solved at resolutions of up to 1.10 A 739799 1.14.99.54 hybrid quantum mechanics and molecular mechanics investigation of the first steps of the LPMO mechanism, which is reduction of CuII to CuI and the formation of a CuII-superoxide complex. In the complex, the superoxide can bind either in an equatorial or an axial position. The equatorial isomer of the superoxide complex is over 60 kJ/mol more stable than the axial isomer because it is stabilized by interactions with a second-coordination-sphere glutamine residue 743929 1.14.99.54 modeling of structure. The divalent metal ion in the active site is coordinated by the three amino acids, His1, His68 and Tyr153. LPMO9A comprises two disulfide bridges, Cys126-Cys208 and Cys38-Cys156 740207 1.14.99.54 single-molecule study by atomic force microscopy 745866 1.14.99.54 structure determined at pH 3.5, shows significant disorder of the active site in the absence of substrate ligand 740264