ERRAT Structure Submission Page

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ERRAT is a protein structure verification algorithm that is especially well-suited for evaluating the progress of crystallographic model building and refinement. The program works by analyzing the statistics of non-bonded interactions between different atom types. A single output plot is produced that gives the value of the error function vs. position of a 9-residue sliding window. By comparision with statistics from highly refined structures, the error values have been calibrated to give confidence limits. This is extremely useful in making decisions about reliability. For more information on the program ERRAT, click here or refer to the paper by Colovos and Yeates.

The coordinates should be submitted in PDB format. To submit a crystal structure for analysis, simply select it with the file dialog which is activated by clicking on the Browse button below, then click the Send File button and away we go...

This version of ERRAT is no longer supported.

If you would like to use ERRAT alone, please use one of these:

Sorry for the change, but old things do break down and new ones take their place.

If you have any questions or complaints, please contact holton at

ERRAT takes just a couple of seconds to run and finish.

If it takes longer than about 10 seconds, it is hanging and is most likely due to problems with the input file that were difficult to correct. If it hangs, please contact us holton at so that we can look into the problem in order to provide a fix for the future.
A couple of most recent problems include
  • All ATOM records on 1 line, with no line breaks.
  • Input file, contained broken ATOM records, like this
    ATOM   1551  CD  LYS A 203      69.744   0.269  55.207  1.00 99.99
    ATOM   1ATOM    830  O   THR A 109      41.312   2.953  46.701  1.00  8.41
    ATOM    831  CB  THR A 109      40.445   6.070  46.060  1.00  8.07
    This can occur when very large files are copied to new files. This cannot be processed by ERRAT, nor can it be reliably corrected.