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 1.2 A resolution X-ray diffraction data, room-temperature neutron diffraction data to 2.12 A resolution 739826 1.14.99.54 to 1.2 A resolution, P21 space group with two protein molecules with non-crystallographic symmetry per asymmetric unit. Role for a conserved histidine in promoting oxygen activation 739859 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 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 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 structure determined at pH 3.5, shows significant disorder of the active site in the absence of substrate ligand 740264 1.14.99.54 to 1.75 A resolution. Stucture reveals a copper-bound active site common to LPMOs, a collection of aromatic and polar residues near the binding surface that may be responsible for regioselectivity, and substantial differences in loop structures near the binding face. Surface analysis reveals energy wells whose spacing seems adapted to the spacing of cellobiose units along a cellulose chain 740707 1.14.99.54 to 1.3 A resolution 741336 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