[ccp4bb]: Odd space group

[Hal Lewis <hlewis@bnl.gov>]

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Hello,

I'm having trouble with a MAD dataset I've collected. The protein appears
to index well in P212121 (i.e. predictions match spots well) with the cell
being 57.6  68.5 125.4  90.000  90.000  90.000. However the Rmerge of the
data is high due to apparent problems with the space group I've chosen. The
Scalepack output shows many examples of:

        0   17    7       150.0       154.5      3.93
        0 -17  -7 a     37       9.8      320.4  100       27.1
        0 -17  -7 a    143       0.3       60.9    0       18.8
        0  17  -7 a     37      11.8      352.5  100       25.4
        0  17  -7 a    144      -0.3       54.3    0       19.3

        0   18    7        90.4       936.7      3.72
        0 -18  -7 a     36      -0.7      576.3    0       82.8
        0 -18  -7 a    142       9.6     1596.1  100      109.5
        0  18  -7 a     37       0.7      640.0    0       84.9
        0  18  -7 a    143       7.8     1530.5  100      123.8

        4   20   30       108.3      1042.7      2.61
        4 -20 -30 a+    32       0.3     1675.2    0       97.9
       -4  20 -30 a+   148      -6.3      543.6  100       95.1
       -4 -20 -30 a-   147      -5.8      628.9  100       95.1
        4  20 -30 a-    33      -0.3     1616.2    0      128.2

        7    1   13       135.0      1474.9      6.24
        7   1  13 f+   135       0.1     2059.8    0      129.2
       -7  -1  13 f+    46      -5.2     1026.7   98      134.7
        7  -1 -13 f+    55      -5.4     1033.4   99      122.3
       -7   1 -13 f+   126       0.4     2103.2    0      134.5
       -7  -1 -13 f-   126       0.0     2036.4    0      155.1
        7   1 -13 f-    55      -5.7      970.8  100      123.4
       -7   1  13 f-    46      -6.1      897.2  100      122.5
        7  -1  13 f-   135      -0.4     1983.4    0      124.8

etc. It appears that symmetry-related reflections aren't truly
symmetry-related (e.g. I have the wrong space group). I've even tried
indexing in P1 with the same result. Any idea what's going on here?  I've
collected the data twice (different crystals) on different dates to try to
eliminate machine or crystal problems. Thanks for any help you can give me,

Hal


Dr. Hal Lewis
Biology Department
Brookhaven National Laboratory

(631)344-4789
hlewis@bnl.gov