Hello,
I need an advice on how to fixate a peptide in 20% SDS PAGE after staining with CBB.
Because it apparently diffuses after a while.
Thank You

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do you think in terms of polypeptides? common CBB solutions are for a combined fixation and staining:
use 0.25 %(w/v) CBB in 1:4:6 acetic acid:ethanol:water

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I mean peptide from 2-5 kDa, we use for staining CBB in 50% MeOH and acetic acid, but it difuses, when i put the gel in 7% acetic acid

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I think drying of the gel or subsequent blotting is the best way to preserve separated peptides

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the 7% acetic acid is enough to maintain fixation but, if you removed methanol then the gell will swell. this will make the band look diffuse (and you may actually lose some).

so, keep the methanol around (30% is good).

you could also fix with tca (will precipitate cbb, so make sure you destain well) or a little formaldehyde (as with silver stain).

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thank you both

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