> There are things you can expect to learn from a
> 2Å structure that you are unlikely to learn from a 5Å structure, even
> if equal care has been given to both experiments, so it makes sense
> for the title to give the potential reader an idea which of the two
> cases is presented. But for this purpose it isn't going to matter
> whether "2Å" is really 1.8Å or 2.2Å.
What should the title say when a crystal diffracts to, lets say, 3 A in one direction and 4-5 A in others?
Alex Aleshin,
Sanford-Burnham Medical Research Institute
10901 North Torrey Pines Road
La Jolla, California 92037
On May 31, 2012, at 2:50 PM, Ethan Merritt wrote:
> On Thursday, May 31, 2012 02:21:45 pm Dale Tronrud wrote:
>> The resolution limit of the data set has been such an important
>> indicator of the quality of the resulting model (rightly or wrongly)
>> that it often is included in the title of the paper itself. Despite
>> the fact that we now want to include more, weak, data than before
>> we need to continue to have a quality indicator that readers can
>> use to assess the models they are reading about. While cumbersome,
>> one solution is to state what the resolution limit would have been
>> had the old criteria been used, as was done in the paper you quote.
>> This simply gives the reader a measure they can compare to their
>> previous experiences.
>
> [\me dons flame suit]
>
> To the extent that reporting the resolution is simply a stand-in
> for reporting the quality of the model, we would do better to cut
> to the chase. For instance, if you map the Molprobity green/yellow/red
> model quality scoring onto good/mediocre/poor then you can title
> your paper
>
> Crystal Structure of Fabulous Protein Foo at Mediocre Quality
>
> [\me removes flame suit from back, and tongue from cheek]
>
>
> More seriously, I don't think it's entirely true that the resolution
> is reported as an indicator of quality in the sense that the model
> is well-refined. There are things you can expect to learn from a
> 2Å structure that you are unlikely to learn from a 5Å structure, even
> if equal care has been given to both experiments, so it makes sense
> for the title to give the potential reader an idea which of the two
> cases is presented. But for this purpose it isn't going to matter
> whether "2Å" is really 1.8Å or 2.2Å.
>
>> Now would be a good time to break with tradition and institute
>> a new measure of quality of diffraction data sets. I believe several
>> have been proposed over the years, but have simply not caught on.
>> SFCHECK produces an "optical resolution". Could this be used in
>> the title of papers? I don't believe it is sensitive to the cutoff
>> resolution and it produces values that are consistent with what the
>> readers are used to. With this solution people could include whatever
>> noisy data they want and not be guilty of overstating the quality of
>> their model.
>
> We should also encourage people not to confuse the quality of
> the data with the quality of the model.
>
> Ethan
>
> --
> Ethan A Merritt
> Biomolecular Structure Center, K-428 Health Sciences Bldg
> University of Washington, Seattle 98195-7742
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