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Hi,<br>
<br>
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.8ex;border-left:1px #ccc solid;padding-left:1ex">1) When
is a good time to start building the peptide into the
density (should I wait until Rfactors improve
significantly)?<br>
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<div>I would advise waiting until the rest of the model is
as good as possible.� That way you can use the difference
map as a paper figure without needing to do any extra
refinement to remove model bias later.</div>
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<br>
It's good to keep in mind that in this case map will be biased by
the non-atomic model (bulk-solvent), as well as by the atomic model
as shown here: Acta Cryst. (2002). A58, 270-282. <br>
<br>
Also note, more (correct) model you build - better map you get - so
even more model you can build.<br>
�
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3) What is a general good strategy for lowering Rfactors?
(Esp if the gap between Rwork and Rfree is high..like
28/40 or so)?<br>
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<br>
28/40 sounds worrying. In majority of scenarios I've seen so far
such a big difference between Rfree and Rwork indicates a problem
that is typically out of scope of refinement.<br>
<br>
Pavel<br>
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