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Re: [ccp4bb]: PEG/isopropanol crystals



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Hi Gloria,

You might also consider transferring your coverslip containing the
crystals over a well solution containing a higher concentration of PEG 4K
(but without any isopropanol) and allowing the isopropanol to diffuse out
of the drop. If the crystals are stabilized in this manner you may not
need to worry about the presence of isopropanol in subsequent
cryoprotection steps. In my case crystals growing in 13% isopropanol and
10% PEG 4K could be stabilized when placed over 30% PEG 4K. 

John

------------------------------------------------------

John R. Walker, Ph.D.
Memorial Sloan-Kettering Cancer Center 
Box 238, 1275 York Avenue
New York, New York
10021
Tel: (212) 639-6713 FAX: (212) 717-3135

------------------------------------------------------

 

On Mon, 27 Jan 2003 gborgstahl@unmc.edu wrote:

> Hello ccp4-ers, 
> Sorry for yet another non-ccp4 related question.
> 
> We have beautiful crystals grown from 9% PEG4000 and 6% isopropanol.
> I anticipate that they may be difficult to freeze in the loop due to the 
> evaporation of isopropanol.
> 
> Does anyone have any suggestions for cryocooling these crystals.
> I've thought to try the various oils.  But perhaps we need to substitute 
> the isopropanol 
> with another organic solvent by soaking. 
> 
> Has anyone had any success cryocooling isopropanol grown crystals?
> 
> Thank you in advance, Gloria
> 
> ******************************************************************************
> Gloria Borgstahl 
> Eppley Institute for Cancer Research
> 987696 Nebraska Medical Center 
> 10732A Lied Transplant Center 
> Omaha, NE 68198-7696
> 
> Office (402) 559-8578
> FAX (402) 559-8577
> 
> Associate Professor 
> Interests:  Cancer, Biochemistry, DNA Metabolism, 
> Protein Crystallography, Super-fine phi slicing, Synchrotron 
> Radiation, Crystal Mosaicity, and X-ray Topography
> ******************************************************************************