On 04/19/11 14:18, Stephane Richard wrote:
Dear CCP4 community,
I have a question a bit off CCP4 topic, but that could use so expert input.
While discussing about a bacterial secreted hemophore (heme scavenging
protein) for which the apo form has been solved, it seems that attempts to
obtain the Heme bound form are failing; in fact during data collection on a
supposed Heme bound form, not only the Iron state changes (reduction), but
the Heme position seems to be affected too. Would anybody have some
experience with such a system and care to send some inputs (off line is fine
as we are here a bit off topic)? Thank you in advance for your help. Best
regards and Happy Building,
Steph
1) "supposed heme bound form" - I would imagine the colour difference
should be quite clear.
2) Reduction - this is a well-known phenomenon. If it causes problems,
you could pursue the strategy of Berglund, Carlsson, Smith, Szoke,
Henriksen and Hajdu (23 May 2002), Nature 417, 463-468.
Briefly, they collected data from multiple crystals and binned the
images by X-ray exposure, thus obtaining a series of structures with
different degrees of X-ray induced reduction. They collected their data
at 100 K.
3) Heme position affected - A) At what temperature were data collected?
B) How would you determine that the heme position changed w/o solving
the structure?
Cheers,
--
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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
