On 05/03/2017 02:46 PM, Gerard Bricogne wrote:
Dear Ed,
Have you considered the possibility that it could be a water
stepping in to fill the void created by partial decarboxylation of the
glutamate? That could be easily modelled, refined, and tested for its
ability to flatten the difference map.
Gerard.
Actually some of them do appear decarboxylated. Is that something that can
happen? In the crystal, or as radiation damage?
However when there is density for the carboxylate (figure), it appears
continuous and linear, doesn't break up into spheres at H-bonding distance -
almost like the CO2 is still sitting there- but I guess it would get hydrated
to bicarbonate. I could use azide. Or maybe waters with some disorder.
Thanks,
eab
Figure- 2mFo-DFc at 1.3 sigma, mFo-DFc at 3 sigma, green CO2 is shown for
comparison, not part of the model.
