Rf: EDTA in cell fractionatio

[Stephen R. Lasky, Ph.D. alt.binaries.pictures.erotica.blondes alt.binaries.pictures.erotica.d alt.binaries.pictures.erotica.female alt.binaries.pictures.erotica.male alt.binaries.pictures.erotica.orientals alt.binaries.pictures.fine-art.d alt]

In article <69172.ashendel at aclcb.purdue.edu>, <ashendel at aclcb.purdue.edu> wrote:

Curt, thanks for these #'s, I had forgotten where to find them.

> (Schmid and Reilley, Analytical Chem.  29: 264, 1957), the log Kd values 
> for each ligand and chleator at pH 8.0 are approximately:
> 
>        EDTA        EGTA
> Ca++   -10.5       -10.5
> 
> Mg++    -8.7        -5.2
> 
> The correct statement is that EGTA has an affinity for Magnesium ions that 
> is lower than the affinity of EDTA for Mg++.  EGTA should be used when 
> it is desired to have less impact on [Mg++] than on  [Ca++]. (This often is 
> the case when isolating membranous subcellular fractions or when it is 
> important to keep the nuclei intact.)
> 

It is also useful when following Pelham and Jacksons protocol for making
mRNA dependant retic translation systems.  This uses micrococcal nuclease
which has a strict requirement for Ca++.

SRLasky

-- 
*********************************************************************Stephen R. Lasky, Ph.D.
Roger Williams Medical Center/Brown University
Phone: 401-456-6572       Fax: 401-456-6569       e-mail: Stephen_Lasky at brown.edu
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
"To me at least, 'Yuck' doesn't capture the full essence of death by
neurotoxin."   -Dick Dunn
*********************************************************************