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Hi,
 
To me this looks like a simple redox displacement reaction which has
nothing to do with oxygen. E.g. if one puts a piece of iron in a
coppersulfate solution, the more noble copper ions take electrons from
the less noble iron and will come out of solution as a metal, while the
less noble iron will disolve as ions. The same principle is used by
plating zinc on iron to prevent rust in e.g. cars. The less noble zinc
will provide electrons to protect the more noble iron. 
 
By choosing the right metal, one might indeed be able to very precisely
reduce redox active groups in proteins.
 
My 2 cents,
Herman


________________________________

	From: CCP4 bulletin board [mailto:[log in to unmask]] On
Behalf Of Peter Moody
	Sent: Wednesday, August 01, 2012 3:30 PM
	To: [log in to unmask]
	Subject: Re: [ccp4bb] Iron induced reduction of crystal
	
	
	Take a look at
http://en.wikipedia.org/wiki/Great_Oxygenation_Event
	
	This might suggest you may have used up the available oxygen.
	
	If you would like to try growing your crystals in an oxygen-free
environment, we (in Leicester) have a glove box with a Douglas
Instruments Oryx 4 robot. I know its not exactly handy for Glasgow, but
......
	
	
	On 1 August 2012 13:53, RHYS GRINTER
<[log in to unmask]> wrote:
	

		Hi All,
		
		I'm currently working of a protein with a ferredoxin
protein with anIron-Sulphur cluster. I was harvesting some crystals the
other day and a piece of my scalpel blade broke off and ended up in the
well solution. I Sealed the well without noticing, the shard of iron
oxidised and the crystals lost most of their red colour:
		
		Ordinary crystals:
	
http://s1058.photobucket.com/albums/t401/__Rhys__/?action=view&current=M
BPR_Rodcluster2edit.png
		
		Crystals from Blade containing well:
	
http://s1058.photobucket.com/albums/t401/__Rhys__/?action=view&current=M
BPR_Bleached.png
		
		My explanation for this (If someone has a different one
that'd be great too)
		
		Is that the oxidation of the metallic iron the well,
created reducing conditions in the chamber and reduced the iron-sulphur
cluster (reduced ferredoxin is much less strongly coloured).
		Which got me to thinking...Could this be applied as a
technique to create reducing conditions in protein crystallography, as
the use of reducing agents isn't always practical.
		
		Cheers,
		
		Rhys Grinter
		PhD Candidate
		University of Glasgow