ethanol precipitation of protein - (Jul/27/2012 )

Hi all,

I want to get information about ethanol precipitation method. I have produced a toxin from a fungal species in a volume of 2 liters and I want to purify the toxin by ion exchange chromatography. I will concentrate 50-fold the sample with ultrafiltration and then, I will apply buffer exchange for chromatography. But, because of total protein concentration of culture supernatant is very low (15 mg/2 liters), I am undecided whether or not the ethanol precipitation method cause a serious decrease in the amount of the total protein. Also, I dont want to lose the activity of the toxin. Do I see any problem about using this method? or Should I use centrifugal filters in this regard? I would appreciate if you share your experiences in this regard with me.Thank you

precipitation of proteins, whether with ethanol, acetone, ammonium sulfate, tca, etc, is inefficient at low protein concentrations.

you can use ultrafiltration to concentrate and exchange buffer (diafiltration) then apply the sample to iec.