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Sorry for the coot question...

The question is whether there is a problem drawing symmetry molecules in
coot in space group C2.  Here's the background:


I'm refining and building a structure using refmac and coot in space group
C2.  I have a molecular replacement solution with one dimer (call it dimer
1) in the asymmetric unit.  I've done a round of refinement in REFMAC:

REMARK   3   RESOLUTION RANGE HIGH (ANGSTROMS) :   2.20
REMARK   3   R VALUE            (WORKING SET) :  0.43359
REMARK   3   FREE R VALUE                     :  0.45645
REMARK   3   FREE R VALUE TEST SET SIZE   (%) :  4.7
REMARK   3   BOND LENGTHS REFINED ATOMS        (A):   679 ; 0.014 ; 0.022
CRYST1   91.111   44.071   54.992  90.00 101.23  90.00 C 1 2 1

Working in Coot, I see good density for dimer 1.

Here's the problem.  I also see very strong 2Fo-Fc density indicating a
second dimer (call it dimer 2).  Coot does NOT draw a symmetry molecule in
the density for dimer 2, but several lines of evidence suggest that this
density represents a crystallographic symmetry mate of dimer 1.

1. There is no Fo-Fc density for dimer 2, which indicates that REFMAC thinks
dimer 2 is a crystallographic symmetry mate of  dimer 1.

2. Careful inspection of few residues shows that the density for dimer 2 is
identical to that of dimer 1.

3. I looked at the structure in O.  O draws a symmetry molecule at the
location of dimer 2.

4. I ran neighbors.inp of CNS.  CNS puts a symmetry molecule at the location
of dimer 2.

5. MOLREP refuses to put a second dimer in the asymmetric unit.

Based on these data, I'd like to ask whether anyone has had problems drawing
symmetry molecules in C2 in coot?

Thanks.

Jack 


-- 
John J. Tanner
Professor of Chemistry and Biochemistry
University of Missouri-Columbia
125 Chemistry Building
Columbia, MO 65211
Phone: 573-884-1280
Fax: 573-882-2754
Email: [EMAIL PROTECTED]
http://www.chem.missouri.edu/TannerGroup/tanner.html



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