Re: [ccp4bb]: B factors

["Aleks Roszak" <aleks@chem.gla.ac.uk>]

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Edward Berry wrote:

> ......................................... If you see a 3A structure
> with average atomic B-factor in the 20-30 range, you should ask why
> the data at 1.5 A wasn't used!

and Frank Vondelft wrote:

> .................................... but it's nice to have these
> correlations modelled explicitly, as opposed to them being merely
> "understood", which is why I really like TLS.  And hence, too, the
> improved R-factors after TLS(typically).

So when you run TLS refinement, and the correlated thermal motion is high, you
get residual B's, and the average B, quite low. Those B's are listed in the pdb
file and may suggest, for readers who are unaware about the TLS refinement,
that the B's are somewhat too low for the given resolution.

My examples:
Resolution 2.5A, Wilson plot B = 57, average B from TLS refinement = 33
Resolution 2.7A, Wilson plot B = 54, average B from TLS refinement = 24

And I definitely couldn't collect any higher resolution data for these
crystals.
So one has to be very carefull to draw conclusions based on the individual B
factors found in the pdb file...

Aleks

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* Aleksander W. Roszak, Ph.D.               E-mail: aleks@chem.gla.ac.uk *
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