A number of isomorphous structures of a specific protein
with various inhibitors are refined. The various structures
diffract from 2.4 to 4.0 A. At 2.4 A, several waters can
be located with certainty. Given the fact that the structure has
NCS and a contrained refinement was indicated by the Rfree even
at 2.4 A, the waters at 2.4 A are located using NCS averaged Fo-Fc
and 2Fo-Fc maps as compared to unaveraged maps. At the lower
resolutions, one should weakly restrain the protein to the structure
at 2.4 A. Is it sensible to search for waters at the lower
resolutions? What is the resolution limit for doing so? Is it
sensible to take the waters of the 2.4 A structure and include them
in the lower resolution refinements?
We would appreciate all suggestions. Thank you.