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On Thursday 20 April 2006 08:23 am, Segura Pena, Dario wrote: > > Recently I obtained protein crystal that grew in 60 % MPD. The crystal > diffracts very well to 1.5Å. It seems that an MPD molecule is in the > active center of the enzyme, however the atom C2 of the MPD molecule has a > B factor of 2 after several cycles of refinement with Refmac. What else is in your crystallization buffer? The obvious possibility would seem to be that the molecule is not actually MPD, but rather something with a sulphate or phosphate group. The local environment should also be a big clue. > Does anybody have any idea why the there is such a low B factor for this > atom?.The electron density for the region corresponding to the atom C2 of > the MPD molecule is visible at 5 sigma level in a 2fo-fc map while at 3 > sigma level there is not electron density for the rest of the molecule. > > I will appreciate any ideas or suggestions. > > Sincerely, > Dario > > > -- Ethan A Merritt Biomolecular Structure Center University of Washington, Seattle 98195-7742
