Phase separation

diane h peapus diane at kuchem.kyoto-u.ac.jp
Sun Sep 8 21:50:43 EST 1996


> On Wed, 4 Sep 1996, H.C. Whitaker wrote:
> 
> > I wonder if anyone can help me? Can anyone explain to me (in laymans
> > terms please!) what exactly is happening when phase separation occurs 
> > in the drop when attempting to crystallise a protein?
> > 

and Harry Powell replied:

> In layman's terms;
> 
> If you have a solution that is unsaturated in the protein, it stays in 
> solution. If it is concentrated so that it is at least saturated (and in 
> the absence of any nuclei, e.g. shards of glass, bits of beard... often 
> supersaturated) the protein will start to precipitate. If the 
> precipitation process is done carefully, the precipitation will be in the 
> form of crystals.


   Was the original poster questioning the separation from protein suspension
or solution to solid protein (in crystal or ppte)?

   If you were talking about the oily blobs that separate out of solution,
then I think we are really talking about the protein sequestering elements
of the mother liquor into separate organic and aqueous phases.  In that case,
please try adding some small amphipillic substance, like a little bit of
ethanol.

best wishes
diane h peapus




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