[ccp4bb] how do you specify Heme oxidation state?

[Laurie Betts]

When refining a heme protein in Refmac5, if one uses HEM.cif, what is  
the default oxidation state of the Fe?  Does one get residual density  
if it is specified as Fe3+ but it's really Fe2+?  Or does one infer  
from the ligand bound that it's one or the other?  WE have a hme  
protein that was originally purged with CO but the ligand looks more  
like OH.  But the amout of residual density around the Fe atom changes  
depending on what ligand we put into the refinement. even though we  
always use the HEM.cif.   Yeesh...

THanks

Laurie Betts
University of Pittsburgh
X-ray Crystallography Facility Manager
Department of Structural Biology
3501 Fifth Avenue,
Pittsburgh, PA 15260
412-383-5839
lab...@pitt.edu