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RE: [ccp4bb]: Indexing problem



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Hi

I tip for P2 (/1), but I wouldn't throw P1 away either -- it can happen.
Hard to say without knowing the completeness and breakdown in resolution
bins:  I find Rmerge in the lowest bin is a useful indicator for the
spacegroup, because I tend to be liberal in what I include as "data",
said he, donning a bulletproof vest.  But if possible try to get more
redundant data in P1, so that the scaling comparison makes more sense.

Also, a quick check on the lattice is to do autoindexing using 3 or 4
images well-separated in phi (e.g. 0 45 90 135):  sometimes one lattice
then becomes clearly favoured.  May not work for you, though, it seems
relatively clear, and you imply that it processes well.

By the way, at peril of being retentive, pseudosymmetry is just that:
something that looks like *symmetry*.  e.g. data merges very nicely in
P4 but it turns out that the active site is disordered unless you scale
as P222.  Simply having a=b is not necessarily pseudosymmetry, it could
be just coincidence.

phx.






> -----Original Message-----
> From: Konstantinos Beis [mailto:kb11@st-andrews.ac.uk]
> Sent: Monday, June 24, 2002 10:05 AM
> To: ccp4bb@dl.ac.uk
> Subject: [ccp4bb]: Indexing problem
> 
> 
> ***  For details on how to be removed from this list visit the  ***
> ***          CCP4 home page http://www.ccp4.ac.uk         ***
> 
> Dear All,
> I have collected some data for a new structure and I have 
> problems with my 
> indexing. In Mosflm I get the following possible space groups:
> 
> 17  59     cP   137.26   137.69   153.06    90.1  90.1  90.0
P23,P213,P432,P4232,P4332,P4132
> 16  58     hR   194.36   205.36   247.82    95.2  89.9 118.1 R3,R32
> 15  58     hR   194.36   205.82   247.13    95.1  89.8 118.1  R3,R32
  14  57     tP   137.69   153.06   137.26    90.1  90.0  90.1
P4,P41,P42,P43,P422,P4212,P4122,P41212,P4222,P42212 P4322,P43212
  13  57     oC   205.69   206.06   137.26    90.1  90.1  83.9
C222,C2221
  12  57     mC   205.69   206.06   137.26    90.1  90.1  83.9  C2
  11  56     mC   206.06   205.69   137.26    89.9  90.1  96.1  C2
  10   3     oC   194.47   194.36   153.06    90.0  90.2  89.8
C222,C2221
   9   3     tP   137.26   137.69   153.06    90.1  90.1  90.0
P4,P41,P42,P43,P422,P4212,P4122,P41212,P4222,P42212 P4322,P43212
   8   2     mC   194.47   194.36   153.06    90.0  90.2  90.2   C2
   7   2     mC   194.47   194.36   153.06    90.0  90.2  89.8   C2
   6   1     oP   137.26   137.69   153.06    90.1  90.1  90.0
P222,P2221,P21212,P212121
   5   1     mP   137.26   137.69   153.06    90.1  90.1  90.0   P2,P21
   4   1     mP   137.26   153.06   137.69    90.1  90.0  90.1   P2,P21
   3   1     mP   137.69   137.26   153.06    90.1  90.1  90.0   P2,P21
   2   0     aP   137.26   137.69   153.06    89.9  89.9  90.0   P1
   1   0     aP   137.26   137.69   153.06    90.1  90.1  90.0   P1


> So in Mosflm from 10 to 1 I have good fitting.
> 
> When I put those data in SCALA in all the possible groups I 
> get the following:
> 
                        I/sigma(overall)  multiplicity(overall)
> for p1 Rmerge of 	5%     5.3                  1.7
> for p21 Rmerge of 	11.7%  2.3                  2.2
> for c2 Rmerge of 	11.7%  1.6                  2.2
> for p222, p2221......  17%   1.6                  4.2
> for c222, .......      17%   1.6                  4.2
> for p4, ........       36%   0.8                  4.4
> 
> The I/sigma and redundancy  varies according to the space group
> 
> As you can see my a=b, which I think it causes problems with 
> the right 
> indexing..
> 
> In my Scala files it seems that I have p4 pseudosymmetry.
> 
> In the p212121 space group I have good definition for the h.
> 
> 
> Due to that (misindexing) I have problems with my Molecular 
> Replacement.
> 
> Is there something that I might be doing wrong or something 
> that I have not 
> noticed? Any help or suggestions are welcomed!
> 
> 
> 
> 
> Kostas
> 
> 
> 
> 
> 
> 
> 
> **********************************************
> Konstantinos Beis
> Centre for Biomolecular Sciences
> University of St Andrews
> North Haugh
> St Andrews
> FIFE KY16 9ST
> 
> 
> tel: +44 1334 427265
> email: kb11@st-andrews.ac.uk
> 
> **********************************************
> 
>


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