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Protein Smear in SDS-PAGE after concentrated? - (Jun/22/2009 )

As the title, I am trying to purify a his-tag protein by TALON. The protein can be pull-down successfully. I load 10% of the pulldown product for western and I am able to see the band clearly. However, I use 90% to run SDS-PAGE for bluestaining, I can hardly see the band instead of a smear pattern.

One of my concern is I use vaccum to concentrate the elution from 100ul to 30ul (just to load into the gel), is it possible that the ion concentration is too high to run SDS-PAGE? If it is the case, how I can solve the problem?

Thanks for help!


your sample may have too much salt (you don't elaborate on the buffer in which the protein is suspended). you may also have too much protein in your sample.

have you tried loading the same amount as you do for the western blot?

if it doesn't show up with bluestain (coomassie?) then try silver.