how to concentrate Co-IP protein sample

Zhonglin Chai Zhonglin.Chai at
Mon Mar 15 22:35:44 EST 2004

It depends on how you do your IP. If your antibodies are not crosslinked to the beads, the combining of multiple eluates will give you lots of Ig that may not be ideal. If your problem is the low level of target protein, you may try to increase your lysate concentration as well as the volume (to increase the absolute amount of the target protein in your IP). Alternatively, you may cross-link your Ab to the Protein A or G beads and repeatedly use it to do IP in multiple lysates if you don't like the large volume IP.

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!

Zhonglin Chai, PhD

Molecular Hypertension Laboratory
Baker Heart Research Institute
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