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 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 structure of the catalytic domain, residues 37-230, to 1.08 A resolution. The active site in is formed by residues His-37 and His-144 that coordinate the copper atom in a T-shaped geometry 745380 1.14.99.54 to 3.0 A resolution. The active site of AA14B is constituted by His1, His99 and Tyr176, forming the canonical histidine brace that is exposed at the surface 745847 1.14.99.54 structure of AA9A bound to cellulosic and non-cellulosic oligosaccharides 745861 1.14.99.54 single-molecule study by atomic force microscopy 745866