Pyranose 2-oxidase (P2Ox) is a 270 kDa homotetrameric flavoenzyme that catalyzes the oxidation of D-glucose to 2-keto-D-glucose. P2Ox participates in lignin degradation by white-rot fungi and a tentative role of the enzyme is the production of H(2)O(2) for lignin peroxidases. Crystals of Trametes multicolor P2Ox were grown from monomethylether PEG 2000, sodium acetate, MgCl(2) and Ta(6)Br(12). They belong to space group P2(1), with unit-cell parameters a = 99.9, b = 101.7, c = 135.6 A, beta = 90.85 degrees. X-ray diffraction data to 2.0 A resolution were collected using synchrotron radiation. Self-rotation function calculations suggest that the asymmetric unit contains one homotetramer with 222 point-group symmetry.