The reassembled structure of galactose oxidase has been placed in the Gallery. My earlier work on this enzyme was posted, below, on September 30, 2007. I remarked then that the docking could be improved and I have done so in preparing the structure for the Gallery. The improved structure brings the copper centres of adjacent subunits closer together and the surrounding aromatic groups into closer contact. To achieve this I have accepted that the amino-acid chain 148-153 has been displaced by crystallization. This chain links the N-terminal auxilliary domain to the catalytic domain. It is quite likely that the N-terminal domain is also slightly out of place but it does not clash significantly with other subunits. The clash of 148-153 with the symmetry-related subunit can be seen in the reassembled structure but it is an artefact of crystallization.
Galactose oxidase shares many features with other proteins in the Gallery. Like hemocyanin it has pairs of copper-histidine centres but unlike hemocyanin, the partners in each pair are in different subunits. Like hemoglobin, the metal centres are electronically linked by an extended π-electron network. Like neuraminidases, the structural motif that focusses compressive force is a "propeller" of β-sheets. Also like some neuraminidases, galactose oxidase has auxilliary domains. These may have a role in interactions with the oligo- or poly-saccharides that are the natural substrates for both enzymes.
In coming days I will modify the preprint, linked through the 30 September 2007 post, to reflect the improved structure.
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