Hi Doeke, you can take the coordinates of B and do a rigid body refinement against the data from A. If this map is sufficient to reproduce model A (including model building and more refinement cycles), then B is isomorphous to A. You can do this the other way round, and the result may not be the same - hence, the mathematical definition of isomorphous is not identical to the practical use of 'isomorphous' structures when it comes to phasing. You can repeat this for each side of the triangle (each in two directions) in order to label the semantic triangle.
Merry Christmas, more peace on earth and sanity for the elections in 2024! Tim On Wed, 20 Dec 2023 20:15:17 +0000 "Hekstra, Doeke Romke" <[email protected]> wrote: > Dear colleagues, > > Something to muse over during the holidays: > > Let's say we have three crystal forms of the same protein, for > example crystallized with different ligands. Crystal forms A and B > have the same crystal packing, except that one unit cell dimension > differs by, for example, 3%. Crystal form C has a different crystal > packing arrangement altogether. What is the right nomenclature to > describe the relationship between these crystal forms? > > If A and B are sufficiently different that their phases are > essentially uncorrelated, what do we call them? Near-isomorphous? > Non-isomorphous? Do we need a different term to distinguish them from > C or do we call all three datasets non-isomorphous? > > Thanks for helping us resolve our semantic tangle. > > Happy holidays! > Doeke > > ===== > > Doeke Hekstra > Assistant Professor of Molecular & Cellular Biology, and of Applied > Physics (SEAS), Director of Undergraduate Studies, Chemical and > Physical Biology Center for Systems Biology, Harvard University > 52 Oxford Street, NW311 > Cambridge, MA 02138 > Office: 617-496-4740 > Admin: 617-495-5651 (Lin Song) > > > > ######################################################################## > > 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/ -- -- Tim Gruene Head of the Centre for X-ray Structure Analysis Faculty of Chemistry University of Vienna Phone: +43-1-4277-70202 GPG Key ID = A46BEE1A ######################################################################## 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/
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