how to concentrate Co-IP protein sample

P.C. PC at
Mon Mar 15 22:00:42 EST 2004

Microcon-3 (from Millipore) should be just fine (you will concentrate 
SDS too to some extent, but that does not matter too much).
You could also elute the protein in acid (Gly-HCl, pH2), and then do TCA 
(may be first neutralize HCl would be safer (?)).

On the other hand, it might be more efficient to upscale and use more 
concentrated extract in your IP with same amount of Ab. Did you check by 
western if you IP most of your HA-tagged protein?


tracy wrote:
> Hi,
> I am trying to do a co-IP experiment on a HA tagged protein, and I eluted
> the protein with SDS buffer.  However, the protein level is very low that
> after I ran the eluate on a gel followed by silver staining, I couldn't see
> any band.  So now I am thinking combining all the eluate from multiple
> experiments.  Is there a way that I can concentrate all these proteins?
> Will TCA precipitation work in the presence of SDS?  Or is there any kind of
> concentrator that I can use?  Thank you very much!

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