Dear Christian, You obviously mean a _non-crystallographic_ trimer -- in a crystallographic trimer the protomers (and their ligands) would be identical by definition. On the other hand, chains related by non-crystallographic symmetry necessarily differ in their environments. As a results of nearby lattice contacts, the properties (average conformation, dynamics, electrostatics etc.) of the binding sites may have become unfavourable for ligand association in two out of three chains in your case. This does not by itself question the relevance of the binding site (provided there is good biochemical evidence), but it does indicate that the ligand is exchanged with the solvent at a rate that is sufficient to allow for such lattice effects. In the end, any conclusion from the crystalline state with respect to the solution state should be thought of as an extrapolation ;-)
Best regards Oliver ================================================== PD Dr. Oliver H. Weiergräber Institut für Biologische Informationsprozesse IBI-7: Strukturbiochemie Tel.: +49 2461 61-2028 Fax: +49 2461 61-9540 ================================================== ________________________________________ From: CCP4 bulletin board [CCP4BB@JISCMAIL.AC.UK] on behalf of Christian GALICIA [christian.galicia.diaz.sant...@vub.be] Sent: 27 October 2020 11:19 To: CCP4BB@JISCMAIL.AC.UK Subject: [ccp4bb] ligand bound to only one chain in the crystal Hello, In our structure only one chain in a crystallographic trimer (non-biological) shows a ligand bound to it (with clear density). There doesn't seem to be any channels (or lack of them) favoring that specific site. Can the community give your opinion on whether this can make the presence of the ligand or its biological role questionable, and give any examples of similar cases you might be aware of. Thank you. -- Christian Galicia Post Doctoral Scientist E-mail: cgali...@vub.be<mailto:cgali...@vub.be> ________________________________ To unsubscribe from the CCP4BB list, click the following link: https://www.jiscmail.ac.uk/cgi-bin/WA-JISC.exe?SUBED1=CCP4BB&A=1 ------------------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------------------ Forschungszentrum Juelich GmbH 52425 Juelich Sitz der Gesellschaft: Juelich Eingetragen im Handelsregister des Amtsgerichts Dueren Nr. HR B 3498 Vorsitzender des Aufsichtsrats: MinDir Volker Rieke Geschaeftsfuehrung: Prof. Dr.-Ing. Wolfgang Marquardt (Vorsitzender), Karsten Beneke (stellv. Vorsitzender), Prof. Dr.-Ing. Harald Bolt ------------------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------------------ ######################################################################## To unsubscribe from the CCP4BB list, click the following link: https://www.jiscmail.ac.uk/cgi-bin/WA-JISC.exe?SUBED1=CCP4BB&A=1 This message was issued to members of www.jiscmail.ac.uk/CCP4BB, a mailing list hosted by www.jiscmail.ac.uk, terms & conditions are available at https://www.jiscmail.ac.uk/policyandsecurity/
