Re: [ccp4bb]: Very low B factor after Refmac

[Laurence Pearl]

then it probably isn't MPD ... What are the interacting residues ? do you have any electron rich cations/anions in the buffer ? maybe its a hydrated ion .. On 20 Apr 2006, at 16:23, Segura Pena, Dario wrote: ***  For details on how to be removed from this list visit the  *** ***          CCP4 home page http://www.ccp4.ac.uk         *** Dear all, Recently I obtained protein crystal that grew in 60 % MPD. The crystal diffracts very well to 1.5 Ǻ. 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. 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 --------------------------------------------------------------------------   Laurence H. Pearl   Section of Structural Biology, Institute of Cancer Research    Chester Beatty Laboratories,  237 Fulham Road, London SW3 6JB, UK   Phone +44-(0)20 7153 5422 : Secretary +44-(0)20 7153 5443   FAX   +44-(0)20 7153 5457 : E-Mail [EMAIL PROTECTED] --------------------------------------------------------------------------   " Live Simply and do Serious Things .. " - Dorothy Crowfoot Hodgkin --------------------------------------------------------------------------