Hi I have this antibody that I need to run on gel. But it's been purified under high salt conditions (0.5M NaCl). I know that the gel will give me problems if I run it under the high salt. However, I have been told I can microdialyze my protein. but how??

Pierce makes microdialysis cassettes.

As for your actual problem, samples with high salt tend to be more conductive. Thus, when sample salt concentrations are way higher than the gel salt concentration, current selectively flows in the region near the sample, rather than uniformly throughout the get. Since migration depends on the current flow, samples will run faster in regions of high current flow, in this case in the region containing high salt samples.

This can be simply solved by dialyzing your sample prior to loading OR by making a gel with a higher salt concentration. High-salt gels run warmer, and may need to be run at a lower voltage than a normal gel (active cold circulation, or running it in a cold room also helps).

If you don't want to get the Pierce microdialysis system, I just found a brochure for a Novagen D-Tube Dialyzer - it looks like a tube with windows where the dialysis membranes are. Also, we routinely use the 500ul Pierce dialysis cassette - that can simply be placed in a styrofoam holder, and kept in a beaker for dialysis.

Thank you all for helping. make's lots of sense.