Re: [o-info] Deleting individual atoms

From: AE Maris (maris@mbi.ucla.edu)
Date: Fri May 24 2002 - 17:29:57 CDT


Not directly O-related, but regarding this old but interesting topic, I 
have come across a recent structure 1gxp which brings me to wonder about 
the "morality" of setting occupancies to zero.  How can 129 atoms have 
no occupancy and yet when a microbiologist pulls the structure up in 
Rasmol, they look present?

One benefit I can see is that if the microbiologist looks at the missing 
atoms list in the pdb header, they are not listed as missing.  What 
would the R factor be with the missing atoms included?  Is this why the 
Wilson B is 62 and the average B is 42?  It's not obvious why these 
atoms were set to zero occupancy.  B-factors for the whole structure 
range from 2 to over a hundred.

There are a few other discrepancies, such as the DNA listed in the 
COMPND field is a 22-mer, but the in the DBREF field is a 23-mer, but if 
you look at occupancy and B-factors, it's not clear what's going on with 
the DNA.  Thanks for any comments regarding how to interpret these 
findings.

Mary Kopka and Ann Maris


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Ann E. Maris
Dept. Chemistry & Biochemistry
University of California Los Angeles
Los Angeles, CA 90095-1569
USA, Earth
(310) 206-8278  FAX (310) 267-1957
http://www.doe-mbi.ucla.edu/people/maris/maris.html



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