Hi Robbie

I don't see that anisotropic truncation has anything to do with the low
spherical completeness as compared with the info in the co-ordinate file.
Yes the spherical completeness after anisotropic truncation will be
reduced, but why would it cause it to become inconsistent with that
reported (unless of course the completeness calculations were performed on
two different reflection files)?  Besides, the anisotropy is quite low (Delta-B
eigenvalues: 3.42  -1.95     -1.47) so that couldn't explain it.

I do agree that something has clearly gone wrong with the reflection
deposition for 6RJY.  It could of course go right back to the collection or
processing, but I think it unlikely anyone could solve the structure with
data in this state!  Approximately alternate reflections are missing, but
the pattern of absences does not correspond with any space group.  For
example from MTZDUMP on the reflection file:

   3   1   0        0.00     21.21      0.22
   3   1   2        0.00     23.83      0.19
   3   1   4        0.00     34.71      0.26
   3   1   6        0.00      9.06      0.11
   3   1   8        0.00     31.64      0.24
   3   1  10        0.00     31.22      0.25
   3   1  12        0.00      1.28      0.39
   3   1  14        0.00      6.59      0.12
   3   1  16        0.00     17.58      0.15
   3   1  18        0.00      3.94      0.18
   3   1  20        0.00     11.05      0.12
   3   1  22        0.00     34.24      0.24
   3   1  24        0.00     12.39      0.14
   3   1  26        0.00     12.76      0.15
   3   1  28        0.00     20.80      0.18
   3   1  30        0.00     23.70      0.19
   3   1  32        0.00     23.47      0.20
   3   1  34        0.00     30.50      0.23
   3   1  36        0.00     10.93      0.22
   3   1  38        0.00     28.11      0.22
   3   1  40        0.00     24.41      0.21
   3   1  42        0.00     11.04      0.21
   3   1  44        0.00     12.58      0.28
   3   1  47        0.00     10.54      0.29
   3   1  49        0.00     10.54      0.23
   3   1  51        0.00      2.98      0.70
   3   1  53        0.00      5.84      0.39
   3   1  55        0.00      9.79      0.27
   3   1  57        0.00     11.33      0.26
   3   1  59        0.00      8.99      0.30
   3   1  61        0.00      1.84      0.76
   3   1  63        0.00      2.63      0.78
   3   1  65        0.00      4.91      0.46
   3   1  67        0.00      3.50      0.64
   3   1  69        0.00      1.93      0.76
   3   1  71        0.00      4.57      0.52
   3   1  73        0.00      1.71      0.73

Note how the pattern switches between (3 1 44) and (3 1 47).

So sometimes k+l = 2n are absent and sometimes k+l = 2n+1 are: this pattern
pervades the whole dataset so the completeness (both spherical and
ellipsoidal) is reduced by a factor of about two.  This makes no sense
in terms of known systematic absences, and certainly not for the reported
space group P212121.  This alternating pattern of absences is of course
extremely unlikely in valid data: normally low completeness arises from
whole missing wedges of data, or cusps, or to a smaller extent detector
gaps, i.e. usually missing data are largely contiguous, not alternating as
here.

I think the only solution here is to get the authors to deposit the data
correctly: is there any commonality of the authors for the structures where
you have noted this problem?

Cheers

-- Ian


On Sat, 30 May 2020 at 09:36, Robbie Joosten <robbie_joos...@hotmail.com>
wrote:

> Hi Everyone,
>
> I've been looking at some recent PDB entries that have much lower
> spherical) completeness than reported in the coordinate file. One reason
> for this is that the data were anisotropicly truncated, another reason is
> some mess-up with the deposition of the reflection data. There is a lot of
> discussion about the former practice and I don't want to go in to that, but
> the second one is obviously an error. Now how do I distinguish these cases?
>
> Sometimes, you can look at the reported number of reflections and compare
> that to the deposited reflection file and you will find that something has
> clearly gone wrong. However, the reported number of reflections is not
> entirely reliable because of other issues so I'd rather not use it. If you
> use PDBpeep (e.g. for 6rjy) you can see something is wrong, but that is
> completely visual. Is there a tool in CCP4 that reports both spherical and
> ellipsoidal completeness (on merged reflection data)? That would make it
> easy to distinguish such cases.
>
> Cheers,
> Robbie
>
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