Hi Matthias, what is the space group? It may help to work with a lower symmetry (i.e. that could remove the 2-fold symmetry axis going through the middle of your dimer), which may give for example 2 molecules in the asymetric unit, and instead refine this with non-crystallographic symmetry (NCS) restraints. Best, Bruno ########################################################################### Bruno P. Klaholz Centre for Integrative Biology Department of Integrated Structural Biology Institute of Genetics and of Molecular and Cellular Biology 67404 ILLKIRCH CEDEX FRANCE http://www.igbmc.fr/Klaholz http://www.igbmc.fr/grandesstructures/cbi http://frisbi.eu http://instruct-eric.com https://inext-discovery.eu -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Matthias Uthoff Sent: 27 April 2021 18:01 To: [email protected] Subject: [phenixbb] Refinement of a b-Strand swapped into the sheet of the symmetry related copy Hi phenixbb, I am working on a homodimer. Each protein has an internal b-sheet with three b-strands, however the sheets swap their middle strands. So a sheet consists of one strand from molecule A surrounded by two strands from molecule B or vice versa. As I am at 3 A resolution, I would like to set secondary structure restraints including correct hydrogen bonding between the strands of the two molecules. My problem: There is only one protein in the ASU and the "other" molecule is in deed just a symmetry mate. Phenix is not able to automatically detect this and if I provide the restraints myself, phenix discards them as it is falsely assuming the b-sheet is intramolecularly (all on chain A) and hence the strands are 30ish A apart. What is the best way of refining this feature? Thanks in advance, Matthias -- Matthias Uthoff, PhD Student University of Cologne Institute for Biochemistry Zülpicher Straße 47 D-50674 Cologne Phone: +49 221 470 3211 E-Mail:[email protected] Internet:http://px.uni-koeln.de _______________________________________________ phenixbb mailing list [email protected] http://phenix-online.org/mailman/listinfo/phenixbb Unsubscribe: [email protected]