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Dear David, I would remind that the "molecular-replacement positionning" of molecular envelopes and some methodological features (in comparison with a conventional MR) of this have been discussed in : Urzhumtsev & Podjarny (1995). "On the Solution of the Molecular Replacement Problem at Very Low Resolution: Application to Large Complexes". Acta Cryst. D51, 888-895. Concerning the practical results, at my knowlegde, this was the first step in the ribosome phasing by Nenad Ban in 1999 (while the envelope was from EM and not from SAXS, but this shall not make a difference). Best regards, Sacha Urzhumtsev ________________________________________ De : CCP4 bulletin board [[log in to unmask]] de la part de David Briggs [[log in to unmask]] Date d'envoi : lundi 12 mars 2012 21:10 À : [log in to unmask] Objet : [ccp4bb] Envelope Phasing. Hi CCP4bb, I would like to ask about "envelope phasing" - specifically with SAXS data. There are papers (1) and tutorials (2) describing how this might be done, but I have also found comments on the ccp4bb, such as this one (http://www.proteincrystallography.org/ccp4bb/message11690.html) which are somewhat less optimistic. I get the impression from my reading around that SAXS envelope phasing is somewhat difficult to do unless you have some NCS you can use to help the phase extension process. Does anybody have any opinions/evidence/examples/anecdotes/tips about how SAXS envelope phasing can be done successfully? Cheers, Dave (1) - eg - http://scripts.iucr.org/cgi-bin/paper?dz5081 (2) - eg - http://www.phaser.cimr.cam.ac.uk/index.php/Using_Electron_Density_as_a_Model ============================ David C. Briggs PhD Father, Structural Biologist and Sceptic ============================ University of Manchester E-mail: [log in to unmask] ============================ Webs : http://flavors.me/xtaldave Twitter: @xtaldave Skype: DocDCB ============================