Re: [ccp4bb]: protein oil out

["David J. Schuller" <djs63@cornell.edu>]

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On Tue, 27 Nov 2001, Edward Berry wrote:

> > Sorry this question is not CCP4 related. I am working on a protein which is highly soluble. I can easily concentrate it to
> > 60mg/ml. While the protein was not precipitated from most chemicals (PEG, (NH4)SO4, molonic acid, .....), instead, it is oil out.
> > Does anybody have similar problem before? Any suggestions ? Thanks in advance.
> > 
> Do you mean that these precipitants induce phase separation, 
> with droplets of protein-rich solution separating out from 
> the bulk phase? I don't know if this happens with pure proteins,
> but in the presents of detergents or other additives there
> can be phase separation, with hydrophobic proteins partitioning 
> into the additive-rich phase. Do you have detergents or
> hydrophobic/amphiphillic additives present?

isn't it the other way around?
detergents and other surfactants help the oil and the water to mix. 
when the oil drops appear, try adding 0.1 - 5% of the usual suspects: 
MPD, 1,6-hexanediol, SDS, N-octyl glucoside.

=======================================================================
"No philosophy book would be complete without mentioning doppelgangers."
                                               - Daniel C. Dennett
=======================================================================
                        David J. Schuller
                        modern man in a post-modern world
                        MacCHESS, Cornell University
                        djs63@cornell.edu