Hey Jun, If it's an old batch check and see if you have microorganisms living in the stock or proliferating in the drop - see the paper by Bai et al: doi:10.1107/S1744309107002904 In this paper they demonstrated how they could not reproduce a crystal hit from an old screen up until they realized a fungi that grew in the drop has been secreting protease that chewed up certain part of their protein - once they have utilized in-situ proteolysis they managed to reproduce there crystals with their home-made ingredients and, of course, solve the structure. In line with this, and if it is possible, pickup one of those crystals and run it on a gel as they did so to make sure it is in the correct size and not a truncated version. Good luck, Chen
--- Chen Guttman The Zarivach laboratory for Macromolecular Crystallography Building 39, Room 009B Ben-Gurion University of the Negev POBox 653 Zip Code 84105 Beer-Sheva Israel http://lifeserv.bgu.ac.il/wb/zarivach Tel. +972-8-6479519 Fax. +972-8-6472970 On Tue, Apr 12, 2011 at 13:56, Jun Yong Ha <j...@princeton.edu> wrote: > Hi all, > > Recently, I produced crystals with MBClass1-64 which contains PEG4000, > HEPES-Na and NaCl. But, I struggled to reproduce crystals. I tried to set up > tray with different batch of solution. I got the crystals only from 2008 > solution, but not from fresh ones. I asked technical service of Qiagen, but > they did not have any stock. > > pH between fresh and old solution is the same. I could reproduce crystals > with this old solution 100% when setting up. > > Do you have any experience like this? Is PEG4000 degraded or oxidized? > > Please help me. > > Thanks in advance. >
