Dear Eleanor, I think the best way is to use Mass spectrum to identify the compound. Best regards, Jiyong
在 2017-10-10 00:07:25，Eleanor Dodson <eleanor.dod...@york.ac.uk> 写道： Any anomalous signal?Eleanor On 9 October 2017 at 17:05, Gang Dong <gang.d...@univie.ac.at> wrote: Could it be a formate ion (HCO2−)? _Gang -----Original Message----- From: CCP4 bulletin board [mailto:CCP4BB@JISCMAIL.AC.UK] On Behalf Of Stephen Cusack Sent: Monday, October 09, 2017 5:40 PM To: CCP4BB@JISCMAIL.AC.UK Subject: [ccp4bb] help identifying unknown density Dear All, I am refining the crystal structure of an E. coli expressed protein at 2.65 A resolution. The crystals grew in 0.1 M MES pH6, 0.7 M sodium formate pH 6. Ni-NTA was used in the purification. There are four molecules in the asymmetric unit. A particular histidine in each molecular has clear, strong extra density which looks like a metal bonded to an imidazole nitrogen (distance approx 2 A) with three other co-ordinating atoms in a triangular planar arrangement (see attached screen shot for unbiased extra density, atoms are only put in the density for illustrative purposes). Has anyone seen anything like this ? Any suggestions ? thanks very much Stephen -- ********************************************************************** Dr. Stephen Cusack, FRS Head of Grenoble Outstation of the European Molecular Biology Laboratory (EMBL) Group leader in structural biology of protein-RNA complexes and viral proteins ********************************************************************** Email: cus...@embl.fr Website: http://www.embl.fr Tel: (33) 4 76 20 7238 Secretary (33) 4 76 20 7123 Fax: (33) 4 76 20 7199 Postal address: EMBL Grenoble Outstation, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble Cedex 9, France Delivery address: EMBL Grenoble Outstation, Polygone Scientifique, 71 Avenue des Martyrs, 38000 Grenoble, France **********************************************************************
