EDTA in growth media

Warren Gallin wgallin at gpu.srv.ualberta.ca
Wed Mar 3 19:59:55 EST 1999


In Article <1999Mar3.212220.31589 at ucl.ac.uk>, chen at bsm.bioc.ucl.ac.uk (Chen
Ho An) wrote:
>I've seen a couple of recipes of minimal media with EDTA added, but can't
>work out why it's there.  Does anyone knows the reason?  It occurs to me
>that perhaps EDTA serves a reservoir of divalent cations which can be
>released when needed, but surely EDTA has a higher affinity for the cations
>than enzymes, how else could it inactive enzymes?

    I can think of two possibilities:

    1) If the medium is being used to grow normally adherent cells in
suspension, then the EDTA will keep calcium ion concentration low, thus
preventing integrins and cadherins from acting to either  stick the cells to
the vessel or to each other

    2) If the cells are particularly sensitive to heavy metals, EDTA has a
higher affinity for many metal ions other than calcium and magnesium, so it
would tend to tie up things like zinc and iron before it picked off the
calcium and magnesium; in this case you would also have calcium and
magnesium in the medium.
Warren Gallin
Department of Biological Sciences
University of Alberta
Edmonton,  Alberta     T6G 2E9
Canada
wgallin at gpu.srv.ualberta.ca



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