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
