| Abstract
| - Pyranose 2-oxidase catalyzes the oxidation of a number of carbohydrates using dioxygen;glucose, for example, is oxidized at carbon 2. The structure of pyranose 2-oxidase with the reaction product2-keto-β-d-glucose bound in the active center is reported in a new crystal form at 1.41 Å resolution. Thebinding structure suggests that the α-anomer cannot be processed. The binding mode of the oxidizedproduct was used to model other sugars accepted by the enzyme and to explain its specificity and catalyticrates. The reported structure at pH 6.0 shows a drastic conformational change in the loop of residues454−461 (loop 454−461) at the active center compared to that of a closely homologous enzyme analyzedat pH 4.5 with a bound acetate inhibitor. In our structures, the loop is highly mobile and shifts to makeway for the sugar to pass into the active center. Presumably, loop 454−461 functions as a gatekeeper.Apart from the wild-type enzyme, a thermostable variant was analyzed at 1.84 Å resolution. In this variant,Glu542 is exchanged for a lysine. The observed stabilization could be a result of the mutated residuechanging an ionic contact at a comparatively weak interface of the tetramer.
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