Thank you all for your comments and suggestions! Our bis citrate indeed looks very similar to the lithium biscitrate in David Lawson's structure 1e5k from 2000 (https://www.sciencedirect.com/science/article/pii/S0969212600005189?via%3Dihub).
Cheers and have a nice WE, Gregor ----- PD Dr. Gregor Hagelueken Institute of Structural Biology Biomedical Center (BMZ) Building 13, Rm 2G 022/023 University of Bonn Venusberg Campus 1 53127 Bonn, Germany Phone: +49 228 287-51200 WWW: http://www.isb.uni-bonn.de/ ----- On 26. Feb 2021, 11:39 +0100, Gregor Hagelüken <[email protected]>, wrote: > To follow up: I forgot to mention that there is no Mg2+ in the condition. > We have PEG4K, Sodium citrate, Ammonium sulfate. > Cheers, > Gregor > > > ----- > PD Dr. Gregor Hagelueken > Institute of Structural Biology > > Biomedical Center (BMZ) > Building 13, Rm 2G 022/023 > University of Bonn > Venusberg Campus 1 > 53127 Bonn, Germany > > Phone: +49 228 287-51200 > > WWW: http://www.isb.uni-bonn.de/ > ----- > On 26. Feb 2021, 11:14 +0100, Gregor Hagelüken <[email protected]>, > wrote: > > Hi, > > > > We recently solved a structure where two citrate molecules from the > > crystallisation condition are bound to the protein. They are nicely defined > > in the electron density. There is some difference density between the two > > citrates that looks like a water molecule: > > https://www.dropbox.com/s/9hxyty5f7udlk6q/Screenshot%202021-02-26%20at%2010.43.13.png?dl=0 > > > > So, we have built a water molecule into the difference density. The “water” > > has a roughly tetrahedral coordination sphere with two H-bond donors and > > two H-bond acceptors around it, but the distances are too short (around 1.8 > > Å): > > https://www.dropbox.com/s/5pgxlvt72hngjty/Screenshot%202021-02-26%20at%2010.38.44.png?dl=0 > > https://www.dropbox.com/s/mcqteu5ibu265lo/Screenshot%202021-02-26%20at%2010.41.22.png?dl=0 > > > > We have thought about sodium ions. But looking at citrate structures in the > > CSD, I found that the distances are also too short for sodium. > > If anybody has an idea what might sit between these two citrate molecules, > > please let me know! > > I am of course happy to give any further information. > > > > Cheers, > > Gregor > > > > ----- > > PD Dr. Gregor Hagelueken > > Institute of Structural Biology > > > > Biomedical Center (BMZ) > > Building 13, Rm 2G 022/023 > > University of Bonn > > Venusberg Campus 1 > > 53127 Bonn, Germany > > > > Phone: +49 228 287-51200 > > > > WWW: http://www.isb.uni-bonn.de/ > > ----- > > > > To unsubscribe from the CCP4BB list, click the following link: > > https://www.jiscmail.ac.uk/cgi-bin/WA-JISC.exe?SUBED1=CCP4BB&A=1 ######################################################################## To unsubscribe from the CCP4BB list, click the following link: https://www.jiscmail.ac.uk/cgi-bin/WA-JISC.exe?SUBED1=CCP4BB&A=1 This message was issued to members of www.jiscmail.ac.uk/CCP4BB, a mailing list hosted by www.jiscmail.ac.uk, terms & conditions are available at https://www.jiscmail.ac.uk/policyandsecurity/
