jjmirujo at unav.es
Fri Oct 8 10:51:51 EST 1999
> In article <37FCCEF5.9E9DFB90 at unav.es>, jjmirujo at unav.es (" J.
> Martinez-Irujo") wrote:
> > In fact, both are metal chelons and have similar affinity for Ca2+,
> > EGTA has 100 000-fold more affinity for Ca+2 than for Mg+2 (it is
> > possible to remove calcium leaving magnesium free in solution).
> > Dissociation constants (expressed as pK=-logK) for Ca+2, Mg+2, Ni+2
> > Cu+2 are (respectively)
> > EDTA: 10.7; 8.7; 18.6; 18,8
> > EGTA: 10,9; 5,4; 13,6; 17,8
> What about Zn+2?
> For some reason, I seem to recall that EDTA is also capable of
> chelating Zn+2.
> Peter Pediaditaki
Both molecules strongly chelate Zn2+, EDTA (pK=16.5) and EGTA
(pK=14.5), as well as several other cations (Cd+2, Fe2+, Fe+3, Mn+2,
Hg+2...). The selectivity toward these cations can be exploited, for
example, removing traces of Ni+2, Co+2 or Zn+2 from soluble His-tagged
proteins, leaving Mg+2 free in solution.
No experience, however, on their effect on lysis buffers.
Juan J. Martinez Irujo
Departamento de Bioquimica
Universidad de Navarra
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