Hi Raj, I would definitely 10 mM MgCl2. I would also increases NaCl conc. as 200-250 mM. Also you can try 5 mM DTT.
Good Luck Dev Devendra B. Srivastava Postdoctoral Associate Laboratory of Molecular Biophysics, The Rockefeller University 1230 York Avenue New York, NY-10021, USA Phone: 212-327-7478 (Lab) 339-222-7670 (Mobile) On Wed, Oct 1, 2008 at 6:52 PM, E rajakumar <[EMAIL PROTECTED]> wrote: > Dear All > Sorry for non-crystallography query. I am working on > DNA binding protein, while mixing DNA with protein for > preparing Protein-DNA complex for crystallization, > protein is precipitating. pI of the protein is 9.3 > and in 15 mM HEPES 7.0, 150mM NaCl and 5% glycerol. > Concentration of the protein used for mixing with DNA > is 8 mg/mL. DNA to protein molar ratio is 1.2. Please > advise me how to prevent precipitation. Is changing of > buffer pH and adding divalent cation like MgCl2 can > help in preventing precipitation? > Thanking You > Rajakumara > > > E. Rajakumara > Postdoctoral Fellow > Strcutural Biology Program > Memorial Sloan-Kettering Cancer Center > New York-10021 > NY > 001 212 639 7986 (Lab) > 001 917 674 6266 (Mobile) > > > > Get your preferred Email name! > Now you can @ymail.com and @rocketmail.com. > http://mail.promotions.yahoo.com/newdomains/aa/ >
