Imidazole is basic. If you mix it directly with zinc salts you will get zinc hydroxide. Most screens are prepared by mixing stock solutions. In your case I would make up the screen from 1 M imidazole, pH 7.2, 1 M ZnSO4, and 50% PEG-4000. Add the PEG last. This should work. You may or may not need this specific salt or buffer to get crystals, and could swap them out or change concentration as required. 50 mM buffer may not be sufficient to control condition pH depending on the protein storage buffer composition.
Roger Rowlett On Sep 27, 2011 11:56 AM, "Browning Christopher" < [email protected]> wrote: > Dear All, > > My question might be a bit out of place, but perhaps someone can help. I've screened my protein in the Nuc-Pro screen from Molecular Dimensions and found some crystals in condition B10. They seem to be protein crystals as they are not highly optically active and look different to salt crystals. So condition B10 consist of 10% PEG 4K, 50mM Imidazole pH 7.2, 20mM Zinc sulfate. In the screen, this condition is perfectly clear, but when I try and make my own screen, the whole solution turns white. Apparently, Zinc sulfate/Imidazole can be used for staining SDS-gels, but that does not really help my a lot. Does anybody have an idea how I might be able to keep everything in solution, seeing that the MD guys managed somehow...... I'm a bit desperate as I don't have many hits for this protein. > > Cheers, > > Chris B > > -- > Dr. Christopher Browning > Post-Doctor to Prof. Petr Leiman > EPFL > BSP-416 > 1015 Lausanne > Tel: 0041 (0) 02 16 93 04 40
