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*To*: Jan Abendroth <Jan.Abendroth@uni-koeln.de>*Subject*: Re: dm-averaging*From*: "David J. Schuller" <schuller@uci.edu>*Date*: Tue, 16 Nov 1999 10:21:51 -0800 (PST)*cc*: ccp4bb <ccp4bb@dl.ac.uk>*In-Reply-To*: <3831A074.EB77C177@uni-koeln.de>*Sender*: owner-ccp4bb@dl.ac.uk

*** For details on how to be removed from this list visit the *** *** CCP4 home page http://www.dl.ac.uk/CCP/CCP4/main.html *** you have 6 [presumably] identical copies. how you choose to average them is somewhat arbitrary. 1) you could just do 2-fold averaging within each dimer 2) you could do 3-fold averaging between your various dimers 3) you could do 6-fold averaging of your monomers. from your description, i think perhaps you are doing #1. i am not entirely sure whether you are doing it correctly, your masking choice would require proper symmetry within dimers, and from your description i cannot tell whether that is the case. or perhaps you are trying to do #1 and #2, in which case you really need to check the DM output statistics on overlap removal, because the algorithm is deliberately designed to prevent this. #3 should give you your best phase refinement/extension, assuming you can identify the boundary for a monomer, and this is the one i will address. you only need a mask for one monomer, say A1. then you need to determine operators from A1 to each of the monomers: A1 -> A1 (the identity matrix) A1 -> A2 A1 -> B1 A1 -> B2 A1 -> C1 A1 -> C2 On Tue, 16 Nov 1999, Jan Abendroth wrote: > Dear all, > once again a question concerning a slightly complicated case of dm and > ncs-averaging. > > The situation: > Within the the asymmetric unit of my crystal there are six copies of the > protomer grouped as three dimers A, B and C. > I could determine the following symmetry operators: > inter-dimer: A -> B > B -> C > intra-dimer: A1 -> A2 (from subunit 1 of dimer A to subunit 2 of dimer > 1) > B1 -> B2 > C1 -> C2 > > All symmetry operators are 2-folds with a transition-component. None of > them falls on a crystallographic axis. > > For the symmetry operations A -> B, A -> B and A1 -> A2 I use A as mask, > for B1 -> B2 i use B as mask and for C1 -> C2 C as mask. > > The question: > Are these symmetry operations enough to cover the whole symmetry? > Or do I have to specify the operations A -> C, A1 -> B1, A1 -> B2 ,... > seperately? ======================================================================= People do not usually gaze at one another intently at very close range, unless they are mothers with infants, or doctors with patients, or lovers. - Ursula K. Le Guin ======================================================================= David J. Schuller modern man in a post-modern world University of California-Irvine schuller@uci.edu

**References**:**dm-averaging***From:*Jan Abendroth <Jan.Abendroth@uni-koeln.de>

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