[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [ccp4bb]: divalent ion selectivity



***  For details on how to be removed from this list visit the  ***
***          CCP4 home page http://www.ccp4.ac.uk         ***



Dear Minghui,

>From a CHEMICAL point of view the three species Mg2+, Mn2+, and Zn2+ are,
indeed, very different.

Mg2+ has a significantly smaller radius than Mn2+ and Zn2+, which can have
some influences on the structure.

Mg2+ and Zn2+ are NOT redox active, while Mn is known in the oxidation states
-3, -2, -1, 0, 1, 2, 3, 4, 5, 6, and 7 (even though the Mn2+ species is
relatively stable in aqueus systems).

Mn2+ makes komplexes as a d5 high spin cation, which allows a large variety of
coordination-geometries, while Zn2+ (d10 configuration) is only known in
tetrahedral (4 ligands) and octahedral (six ligands) coordinations. Compare
that e.g. with Cu2+, a d9 cation, which makes planar komplexes instead of
tetrahedral ones for 4 ligands and the octahedral coordination is
significantly distorted due to a Jahn Teller effect.

The coordination geometry of Mg2+ is mostly octahedral with 6 ligands, but
some cases with tetrahedral coordination sphere (4 ligands) are known as well.

I am not sure whether this answers your question (probably not), but that's
all I can contribute.

Best wishes

Peter



Li Minghui <lmh@moon.ibp.ac.cn> said:

> ***  For details on how to be removed from this list visit the  ***
> ***          CCP4 home page http://www.ccp4.ac.uk         ***
> 
> Dear all,
> 
> Can any one tell me from the structural point of view 
> why some kinases have higher activity with Mg2+ ions, while 
> some others prefer Zn2+ or Mn2+.
> And what is the meaning for  this kind of divalent ion selectivity?
> 
> Thank you very much.
> 
> Minghui Li
> 
> National Laboratory of Biomacromolecules 
> Institute of Biophysics, Academia Sinica 
> Tel: 86-10-64888507 
> E-mail: lmh@moon.ibp.ac.cn 
> 

-- 
************************************************************************
Dr. Peter Mueller                                   fon: +1-310-825-1420
UCLA-DOE Laboratory of Structural Biology           fax: +1-310-206-3914
and Molecular Medicine
201 MBI
BOX 95157                           http://shelx.uni-ac.gwdg.de/~peterm
Los Angeles CA 90095-1570           peterm@mbi.ucla.edu
************************************************************************