Here's an example (although not Fe):
Futterer, K., Ravelli, R. B. G., White, S. A., Nicoll, A. J. &
Allemann, R. K. (2008). Acta Cryst. D64, 264-272.
On 8 Apr 2008, at 9:02 AM, Florian Schmitzberger wrote:
Dear All,
Are there prominent examples of ordering of an alpha-helix within a
protein upon metal binding (in particular Fe)?
In my case, I observe that a 10 amino acid fragment seems to become
visible in electron density maps, only upon Fe2+ binding to a
glutamate (the first amino acid of the respective 10 residues). The
fragment is part of a larger alpha-helix (which is ordered
irrespective of metal binding). The 10 residue part (including the
Glu) is not visible in the iron-free crystal structure in this
subunit of the homodimer.
I don't think that the helix is necessarily unfolding/folding,
since in the other subunit in the asymmetric unit it is visible in
the absence of Fe (probably due to crystal contacts). I am unsure
about the significance, as it is only in one of the two subunits in
the asym. unit that I see the ordering.
Thank you very much in advance for any comments!
Florian
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