Ascorbate oxidase azide form

E. X-Ray Structure of the Azide Form of Ascorbate Oxidase The Catalytic Mechanism... 

Fig. 13. Schematic drawing of the azide form of ascorbate oxidase around the tri-nuclear copper site. The included copper-copper distances are the mean values between both subunits.

Anaerobic reduction of ascorbate oxidase, AOox, by ascorbate ion is an eight-electron process. Initial reduction of the type 1 centre is reversed as the type 3 centre is reduced and it is suggested that type 1 copper is close to the substrate binding site and that type 3 is involved in the interaction with molecular oxygen. Azide, which can bind to type 2 copper, has no effect on the reduction process. A potentially catalytically active intermediate is formed in the reaction between ascorbate oxidase and hydrogen peroxide at pH 7.6, 0.01 M phosphate, and 25 °C ... 

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