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X-Gal solubility

David L. Haviland dhavilan at imm2.imm.uth.tmc.edu
Tue Jan 25 18:01:55 EST 2000

Jim Kami wrote:
>     For some 15 years now I've been dissolving X-Gal in Dimethyl
> Formamide (DMF) as recommended in most cloning manuals. However, I
> recently noticed on a MSDS that X-Gal has an appreciable water
> solubility (0.1 - 1.0 gram/ml ). So I was wondering if anyone knew of a
> specific reason a solvent like DMF is used instead of a less toxic
> solvent like water or ethanol or is this just a historical accident like
> salmon sperm DNA ?

I'd be leary of using water.  You don't want hydrolysis.

Ever since a Biotechniques article I've always used DMSO as a solvent
for X-gal.  It has worked well in all applications including beta-gal
assays, and blue-white library titering.

Hope this helps,
David L. Haviland, Ph.D., Asst. Prof. Immunology 
University of Texas - Houston, H.S.C.
Institute of Molecular Medicine, R907
2121 W. Holcombe Blvd.,  Houston, TX  77030 
If everything seems to be going so well, you have obviously 
overlooked something.

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