i suppose it depends on the concentrations of the samples. If you loaded 5ul of a 1ml crude sample but made up the purified sample in 200ul then I would expect the 5ul loaded sample of this material to be up to 5x stronger because it is more concentrated

The purpose of ammonium sulfate fractionation is as a first step in purification of the protein. If equal amounts of total protein were loaded for the crude extract and the ammonium sulfate fractions, you would hope to see a thicker band of the desired protein in one of the ammonium sulfate fractions, showing that some purification had occurred.

Dear Derdy

I wondering how much crude protein you have loaded? did you measure it? it looks either degraded or you have loaded less than 20 micro gram, because I cannot see a lot of protein in CE lane which is surprising, is it a fresh or old extract and contained protease inhibitors? is it the same extract that you treated with ammonium sulphate? the good thing is 70% fraction looks promising and one step of gel filtration or ion exchange may yielded in a pure protein, it also looks that your target protein is predominant which much easy to purify. 

Good luck

Derdy from your gel it is clear most of your protein precipitates in 70% ammonium sulfate.I think you have loaded equal volume of protein samples and not equal amount of protein sample. After dialysis most of the protein sample get diluted  and so you see a faint band than the ammonium sulfate precipitation. Your only anomaly is for crude where your band is more thick in case of dialysis. I think this may be a case of  exchange of 70% and crude sample.  Hope this will help you.

Its just based on the concentration.  ensure that you load 25-35μg per well.

Your post ammonium sulfate precipitate is more concentrated. I  think that you had applied much protein in your SDS gel. Please try to apply the same amount of protein for extract and post ammonium sulfate precipitate.