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PDB EXPDTA records

Frances Bernstein (bernstei@fcb.pdb.bnl.gov)
Thu, 21 Sep 1995 14:42:44 -0400 

PDB entries contain a record called EXPDTA that describes the
type(s) of experimental data used to determine the structure.
The PDB currently has the following types defined:

       ELECTRON DIFFRACTION
       FIBER DIFFRACTION
       FLUORESCENCE TRANSFER
       NEUTRON DIFFRACTION
       NMR
       NMR SOLID STATE
       NMR SOLUTION
       SYNCHROTRON X-RAY DIFFRACTION
       THEORETICAL MODEL
       X-RAY DIFFRACTION

For NMR entries the keyword can be followed by a comma and additional
information:

EXPDTA    NMR, 29 STRUCTURES
EXPDTA    NMR, MINIMIZED AVERAGE STRUCTURE

If more than one type of experiment was performed the two sets of
information will be separated by a semi-colon:

EXPDTA    X-RAY DIFFRACTION; NEUTRON DIFFRACTION

I was unable to find a field in the mmCIF dictionary that is designed
to carry this information.  Note that we have had several entries
over the years that used more than one type of data so this must be
handled as a list in mmCIF.

I am aware that the NMR people are designing extensions to CIF for
their special purposes but I feel that this aspect must be handled in
mmCIF itself because it is directly relevant to the coordinates of a
macromolecule (and because a joint x-ray and NMR study is not out of
the question).

Would it possible to design keywords and a format to carry this information?

                                   Frances C. Bernstein