Hello Joern, do you have an image of the anomalous difference map as well? Do you see the same 7 peaks there, or only the central blob?
Filip On Thu, Nov 1, 2012 at 11:45 AM, Joern Krausze <jk...@helmholtz-hzi.de>wrote: > Dear all, > > I have two isomorphous crystals of the same protein. One crystal, let's > call it 'derivative', was soaked with 10 mM CoCl2 whereas the other, let's > call it 'original', was not. Both crystals were otherwise grown under > identical conditions (see below) and treated the same. In the derivative, > I see some puzzling electron density which I do not see in the original > (find two pictures under the links below; the waters in the figures are > just put in for your convenience, they were no part of the refinement). > The density forms a planar hexagon of spheres with another sphere in the > exact center. The distance from corner to corner is about 3.0 A but > varies. The distance from one corner to the center is about 3.1 A. The > hexagon is almost symmetrical as the angles enclosed by two edges are > about 120° each. This density shows up at two positions, once located > between two aspartate residues and once between an aspartate and a > tyrosine residue. These are, however, no special postions. It seems > obvious that this density is caused by the presence of Co(II) since it > only shows up in the derivative and also coincides with peaks in the > difference fourier map. I am unable to interpret it in a way that makes > sense. Could anyone of you help me figure out what to build in there? > > Crystallization condition for both original and derivative was 200 mM > Tris pH 8.8, 200 mM NaCl, 21% PEG 6000, 20% glycerol. > > The high-resolution limit of the dataset is 2.0 A. Data were collected at > lambda=0.981 A. Anomalous data were collected at Co peak wavelength (weak > SigAno but good enough for difference fourier map). > > links: > > http://imageshack.us/a/img89/**9376/unknowndensity1q.png<http://imageshack.us/a/img89/9376/unknowndensity1q.png> > http://imageshack.us/a/img696/**7135/unknowndensity2.png<http://imageshack.us/a/img696/7135/unknowndensity2.png> > > Thank you in advance! > > Joern > > ******************************************** > Address: > > Joern Krausze > Molecular Structural Biology > Helmholtz Centre for Infection Research > Inhoffenstrasse 7 > 38124 Braunschweig > Germany > > Email: joern.krau...@helmholtz-hzi.de > Phone: +49 (0)531 6181 7023 (office) > +49 (0)531 6181 7020 (lab) > ******************************************** > > ______________________________**__ > > Helmholtz-Zentrum für Infektionsforschung GmbH | Inhoffenstraße 7 | 38124 > Braunschweig | www.helmholtz-hzi.de > > Vorsitzende des Aufsichtsrates: MinDir’in Bärbel Brumme-Bothe, > Bundesministerium für Bildung und Forschung > Stellvertreter: Rüdiger Eichel, Abteilungsleiter Niedersächsisches > Ministerium für Wissenschaft und Kultur > Geschäftsführung: Prof. Dr. Dirk Heinz; Ulf Richter, MBA > Gesellschaft mit beschränkter Haftung (GmbH) > Sitz der Gesellschaft: Braunschweig > Handelsregister: Amtsgericht Braunschweig, HRB 477 > -- Filip Van Petegem, PhD Associate Professor The University of British Columbia Dept. of Biochemistry and Molecular Biology 2350 Health Sciences Mall - Rm 2.356 Vancouver, V6T 1Z3 phone: +1 604 827 4267 email: filip.vanpete...@gmail.com http://crg.ubc.ca/VanPetegem/
