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Re: [ccp4bb]: divalent ion selectivity



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Dear Dimitry,

I do not think at all that Zr can only be observed as Zr2+. In the e-mail you
refer to I wrote about Zn (zinc) and not Zr (zirconium).

Zr is, at least in water, most happy as Zr4+ (however, as well known in other,
even negative (!), oxiodation states), and can be sourrounded by 6, 7 or 8
ligands (some exotic compounds with other coordinations are knwon, but I do
not know that in detail).

Thus, REHBEL, a structure I am NOT familliar with, can be explained perfectly
well with the normal behaviour of Zr.

Concerning the chemistry of Zn (zinc), I am quite sure that the only stable
species in water is Zn2+. I think there are as well some strange compounds
with (Zn2)2+, where Zn possesses, at least formal, the oxidation state +1 (I
think you can treat Zn(0) with ZnCl2 under certain conditions to form such a
compound, but I'm not sure). I personly think these compounds might be rather
Zn(0)/Zn(II) than Zn(I)/Zn(I), but I really do not know any details.

Have fun with your metals

Peter



Dmitriy Alexeev <D.Alexeev@ed.ac.uk> said:

> Dear Peter,
> What could you say about the electronic state of the Zr-compound called
> REHBEL in CSD? A pdb-type coordinate extract from it is attached. It is
> 7-coordinated. All oxydens except O00, O1,O2,O3 are deprotonated
> tyrosine-like OH groups. What could be the charge distribution here - the 3
> top and 3 bottom oxygens are coordinate to one Li each, so the central
> Zr-oxyde must have a charge of 2- in total? Then it must be Zr+4 - at least?
> I observe a very similar Zr-cluster bound to a protein - why do you think it
> is always Zr+2?
> Dr. Dmitriy Alexeev
> University of Edinburgh
> Michael Swann Building,
> Mayfield Road
> Edinburgh EH9 3JR
> (44) 0131 6507047
> (44) 0131 6507055-fax
> ----- Original Message -----
> From: "Peter Mueller" <peterm@mbi.ucla.edu>
> To: "Li Minghui" <lmh@moon.ibp.ac.cn>
> Cc: <ccp4bb@dl.ac.uk>
> Sent: Thursday, February 28, 2002 12:00 AM
> Subject: Re: [ccp4bb]: divalent ion selectivity
> 
> 

-- 
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Dr. Peter Mueller                                   fon: +1-310-825-1420
UCLA-DOE Laboratory of Structural Biology           fax: +1-310-206-3914
and Molecular Medicine
201 MBI
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