You can manipulate the structure directly by dragging with the mouse. Mouse drag down with Shift key to zoom. Try gestures on touch screen devices. Click on the links below the black box to see other useful views of the structure. Advanced users can select the Console from the function menu and directly enter JSmol commands.
Each chain consists of a catalytic domain and an auxiliary domain. I have labelled them as if separate chains. A, B, C, and D are catalytic domains and E, F, G, and H their respective auxiliary domains. As with other enzymes, the catalytic site is enclosed and physically constrained. Constraint is produced by the focussed compressive stress of four beta-sheet barrels, also known as "propellers", very similar to the structure of neuraminidases. The orientation of the barrels deviates from a regular tetrahedron to provide the optimum spatial distribution of stress for catalysis at the active site. In nature, this enzyme acts on the terminal residue of an oligosaccharide and therefore must provide a passageway through which the oligosaccharide can extend from the outside to the active site.
For further information about this protein, see the paper "Proposed tetrahedral quaternary structure for Galactose Oxidase"referred to in the posts of 30 September 2007 and 10 July 2011 on nativeproteins.blogspot.com
Or contact the author, Dr Don Vanselow at dvanselow@hotmail.com
Further details of JSmol available here