Some alternative interpretations have been suggested, but if you think
you are seeing radiation damage, you could try collecting data on
several crystals and binning it by dose received. For comparison see:
The catalytic pathway of horseradish peroxidase at high resolution.
Berglund, et al. (23 May, 2002) Nature 417(6887), 463-8
DOI:
10.1038/417463a <https://doi.org/10.1038/417463a>
If your low dose and high dose structures appear nearly the same, then
you are seeing something other than radiation damage.
On 11/06/17 06:01, Martin Malý wrote:
Dear colleagues,
I am investigating a structure of a FAD-dependent enzyme. The electron
density map suggests radiation damage to the FAD. It apparently is
different from simple change of the redox state and "butterfly"-like
structure. We did not find in literature possible products of
radiation damage, like a removal of several atoms of the FAD. Has
anyone observed such effect?
To describe it in more detail, I can observe negative difference map
of C2, N3, C4, and O4 atoms of flavine. Moreover, there is positive
difference map close to O2 and O4 atoms thus it looks as water
molecules are bound there instead of the missing FAD atoms.
I am attaching parameters of the experiment: performed at synchrotron,
exposition time 210 s, high resolution diffraction limit 1.65 A
(<I/sigma> = 2 at shell 1.75-1.65 A). We could see a decrease of
diffraction data statistics during the experiment hence we think there
is significant radiation damage to the crystal.
Thank you very much for ideas.
Regards,
Martin Maly
--
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All Things Serve the Beam
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David J. Schuller
modern man in a post-modern world
MacCHESS, Cornell University
schul...@cornell.edu
