unable to ppt. protein using ammonium sulphate

Ding Ming ming at ahabs.wisc.edu
Thu Nov 17 10:07:52 EST 1994


In article <BBE315406CC at microb.umd.edu>, SABLAB at MICROB.UMD.EDU ("S.A.
Benson Lab") wrote:
> I have a problem trying to precipitate a purified protein, I have 
> used almost 60% of ammonium sulphate and actually the solution is 
> saturated and I still don't see any cloudiness. 

This will not be true if you are talking about the aqueous solution and
the percentage is AS saturation. I used to use 80% saturation (about
600g/liter) and the result was pretty good. One of the tricks is that you
may leave the mixture on ice for 30 min, then in the cold room overnight.
In addition, you may need to add one drop of NaOH for each 10 gram of AS
added.



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