Any anomalous signal? Eleanor On 9 October 2017 at 17:05, Gang Dong <[email protected]> wrote:
> Could it be a formate ion (HCO2−)? _Gang > > -----Original Message----- > From: CCP4 bulletin board [mailto:[email protected]] On Behalf Of > Stephen Cusack > Sent: Monday, October 09, 2017 5:40 PM > To: [email protected] > 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: [email protected] > 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 > ********************************************************************** >
