Coomassie stain on Western Blots

Cornelius Krasel krasel at wpxx02.toxi.uni-wuerzburg.de
Fri Feb 11 15:51:15 EST 2000

Martijn van Duijn <dune at dds.nl> wrote:
> Just something I always wondered about.
> When I transfer proteins from a gel to a (pvdf) membrane, they stick to
> the membrane. In a subsequent stain, coomassie binds to the protein, and
> I get nice blue bands. No problems so far.
> But why don't I get a completely blue membrane after a blocking step
> with a protein mix like non-fat milk? I would think that the milk
> protein would both stick to the membrane, and be stained by Coomassie.

I don't know, but we have observed the same when staining blots with
Ponceau S *after* doing a full western blot. I suppose that the amount
of milk protein actually binding to the membrane must be rather
negligible (sp?).


/* Cornelius Krasel, U Wuerzburg, Dept. of Pharmacology, Versbacher Str. 9 */
/* D-97078 Wuerzburg, Germany   email: phak004 at rzbox.uni-wuerzburg.de  SP4 */
/* "Science is the game we play with God to find out what His rules are."  */

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