I am trying to compare structures of the same protein in the apo form and
when bound to several different ligands. There are differences, but they
are subtle and I am unsure whether they are actually significant or just do
to coordinate error or something similar. Is there a theoretical minimum
(in Angstroms maybe?) that a side chain or secondary structure element
needs to be displaced by between structures to be considered to be "real"?
This may depend on resolution/B-factors as well? Phenix reports overall
coordinate error for each structure, but this must vary for at least a bit
for certain amino acid residues just like B-factors do.
