Hi Laurie,
An related, but off-topic comment follows.
This particular issue is well suited to the single crystal
spectrophotometer that we have integrated into beamline X26-C at the
NSLS. We have observed that many heme protein crystals change either
redox state and/or ligand state as a function of x-ray exposure.
These changes are easy to document with correlated spectroscopy and
x-ray diffraction analysis. We operate this facility in a general
user access mode.
AMO
At 11:13 AM 7/15/2009, Laurie Betts wrote:
>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
>[log in to unmask]
******
Allen M. Orville, Ph.D.
Biology Department
Brookhaven National Laboratory
Upton, NY 11973-5000
e-mail: [log in to unmask]
phone 631-344-4739
fax 631-344-2741
http://www.bnl.gov/biology/People/Orville.asp
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