Coomassie blue staining - Protein invisible with Coomassie blue st (Jul/14/2004 )

Hello everybody,

I am isolating some enzymes from E. coli lysates. For one protein I got very strange results: when I do my final chromatography on Mono-Q column I got all activity in fraction which looks completely empty on SDS-PAGE, when I stain the gel with Coomassie blue staining solution. Surprisingly, when I run the fraction again on SDS-PAGE and stain gel with silver staining procedure I got very strong band. OD280 measurement shows present of protein about 1 mg/ml in the fraction. And it is reproducible results. I suggest than protein can not be stain with Coomasie blue but I can find reference that somebody also get similar results.
Does anybody observe similar results for any protein? Or read articles about that? Could you, please, send me the reference?

Alexei Dubrovsky, Miami, USA

Try Ponceau stains.

Hello Alexei,

In my experience I faced this problem many times. Generaly silver staining is indeed known to be more sensitive than Coomassie however it does not apply for all the proteins. For some proteins you can actually find the opposite.
Unfortunetely besides my own experience, I cannot give you any references.
Good luck

Quol