Pyranose 2-oxidase catalyzes the oxidation of a number of carbohydrates usin
g dioxy
gen;
glucose, for example, is oxidized at carbon 2. The structure of pyranose 2-oxidase with the reaction product2-keto-
ges/
gifchars/beta2.
gif" BORDER=0 ALIGN="middle">-
D-
glucose bound in the active center is reported in a new crystal form at 1.41 &Arin
g; resolution. Thebindin
g structure su
ggests that the
ges/
gifchars/alpha.
gif" BORDER=0>-anomer cannot be processed. The bindin
g mode of the oxidizedproduct was used to model other su
gars accepted by the enzyme and to explain its specificity and catalyticrates. The reported structure at pH 6.0 shows a drastic conformational chan
ge in the loop of residues454-461 (loop 454-461) at the active center compared to that of a closely homolo
gous enzyme analyzedat pH 4.5 with a bound acetate inhibitor. In our structures, the loop is hi
ghly mobile and shifts to makeway for the su
gar 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 &Arin
g; resolution. In this variant,Glu542 is exchan
ged for a lysine. The observed stabilization could be a result of the mutated residuechan
gin
g an ionic contact at a comparatively weak interface of the tetramer.