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On Thu, 18 May 2006, Dr. Robert Sean Connell wrote: > *** For details on how to be removed from this list visit the *** > *** CCP4 home page http://www.ccp4.ac.uk *** > > > Hi All, > we have got some nice crystals from these conditions (final > concentrations at the moment of hte setup of the expriment): > > drop: 3.5 % MPD, 10 mM imidazol pH 6 > > reservoir: 17.5 % MPD, 50 mM Imidazol pH 6 > > We tried to harvest the crytals in: > 20 % MPD, 10 mM Imidazol pH 6 > > The crystals completely dissolved after 1.5 hours. > > In which solution you would harvest those crystals? And which solution > you would use for cryoprotection? > > Many many thanks in advance I note that the harvesting solution only has 10 mM imidazole, whereas the reservoir solution contains 50 mM of the compound. During equilibration, there are 2 components that will equilibrate (MPD and imidazole). With the protein drop containing 10 mM imidazole. It might just be that the imidazole ring is involved in mediating crystal-forming interactions. Reducing the imidazole concentration might therefore have a deleterious effect (to be tested!) since it may go out of the crystals slowly. The first test I would do would be to try harvesting in ca. 20 % MPD (could be 18%...) but with 50 mM imidazole. If the same behaviour is observed, then you will have ruled that possibility out (trying to solve problems one at a time!) Fred. -- s-mail: F.M.D. Vellieux (B.Sc., Ph.D.) Institut de Biologie Structurale J.-P. Ebel CEA CNRS UJF 41 rue Jules Horowitz 38027 Grenoble Cedex 01 France Tel: (+33) (0) 438789605 Fax: (+33) (0) 438785494 e-mail: [EMAIL PROTECTED]
