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Figure 1
(a) Schematic view of RvR scatter plot. (b) Observed RvR scatter plot: red, (potential) merohedral twins; black, (potential) pseudomerohedral twins. Green ovals show the area populated by cases with TNCS (labelled A) and the areas corresponding to mislabelled data (labelled B and C). (c) Observed RvR scatter plot (enlargement of Fig. 1[link]b): black, known to be untwinned and not analysed; blue, found to be untwinned after further analysis; green, twins without RPS; red, twins with some degree of RPS, but the difference between the twinning and RPS operators may be quite large. (d) Middle blue curve, results after refinement of PDB entry 1nqh , performed without taking twinning into consideration, against simulated data sets with twinning fractions in the range 0–0.5 with standard restraints on ADPs. Left red curve, the same calculations with relaxed restraints on the ADPs. Right green curve, results before refinement. Here Rtwincalc ≃ 0.5. It is expected that proper twin refinement would preserve this value.

Journal logoBIOLOGICAL
CRYSTALLOGRAPHY
ISSN: 1399-0047
Volume 62| Part 1| December 2006| Pages 83-95
doi:10.1107/S0907444905036759
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