Galactose oxidase inner sphere

It is interesting to consider the effect of exogenous ligands (which have previously been shown to bind to the Cu(II) atom inner sphere by ESR studies (22)) on the optical spectrum of galactose oxidase. (While... 

Galactose oxidase hinds a single copper ion within Domain 11 on the axis of the wheel. The active site (Fig. 5) is unhke any other biological copper complex, an appropriate distinction for this remarkable enzyme. To explore the site in more detail, the protein environment of the mononuclear copper center may be separated into (A) direcdy coordinated metal hgands (hrst shell, inner sphere interactions) and (B) the extended active site environment (the second shell or outer coordination sphere). 

Fig. 7. Inner sphere of the galactose oxidase copper-binding site. Geometric details of the ligand arrangement in the aquo complex are indicated in the figure. (Based on protein coordinates PDB ID IGOG.)...

Fig. 21. Proposed catalytic mechanism for substrate oxidation by galactose oxidase. (A) Substrate binding displaces Tyr-495 phenolate which serves as a general base for abstracting the hydroxylic proton. (B) Stererospecihc pro- hydrogen abstraction by the Tyr-Cys phenoxyl radical. (C) Inner sphere electron transfer reducing Cu(II) to Cu(I). (D) Dissociation of the aldehyde product.

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