You should try X-ray fluorescence measurements on your crystals You'll see directly the presence of Zn or Ni You can also perform a data collection at energies at both sides of max f" for Zn and Ni. ----- Christine Cavazza iRTSV/Laboratoire de Chimie et Biologie des Métaux CEA Grenoble 17 rue des Martyrs 38054 Grenoble cedex 09 Tel. : (33) 4 38 78 91 21 Fax : (33) 4 38 78 91 24 Email: christine.cava...@cea.fr
De : Dhanasekaran Varudharasu <dhana...@gmail.com<mailto:dhana...@gmail.com>> Répondre à : Dhanasekaran Varudharasu <dhana...@gmail.com<mailto:dhana...@gmail.com>> Date : mardi 1 juillet 2014 17:10 À : "CCP4BB@JISCMAIL.AC.UK<mailto:CCP4BB@JISCMAIL.AC.UK>" <CCP4BB@JISCMAIL.AC.UK<mailto:CCP4BB@JISCMAIL.AC.UK>> Objet : [ccp4bb] Metal ion differentiation - reg Dear all, I have solved a structure (using molecular replacement) of metallo-enzyme which may have Zn or Ni at its active site. I collected data at in-house CuKa radiation. Now, I am able to locate the active site metal ion preciously but I am not able to differentiate whether it is Zn or Ni. I computed anomalous difference map and I got good anomalous map also. But still there is ambiguity, since Zn and Ni have closest F" values at CuKa radiation ( For Zn = 0.68 and For Ni = 0.51). But both, Zn and Ni have different F' values at CuKa radiation ( For Zn = -1.61 and For Ni = -3.07). My question is that, Can we used F' value information to differentiate metal ions?. Is it possible to find whether I have Zn or Ni at active site of my enzyme using crystallographic technique?. Thanks in advance -- Dhanasekaran Varudharasu Post-Doctoral Fellow Department of Oral Biology Rutgers school of Dental Medicine Rutgers Biomedical and Health Sciences Newark, NJ 07103 USA
