Hi Cedric, I presume you collected the datset at a synchrtron source. It could be free radical generated due to X-ray radiation has modified the glutamate residues. I have seen this happening for Ser residues.
Cheers, Shiva On Wed, May 18, 2011 at 9:08 AM, cedric bauvois <cbauv...@gmail.com> wrote: > Hi, everyone, > > I am working on the refinement of a structure at about 1.4 Ang and found > some clear extra density connected to a glutamate (see figure), but I > don't know what it should be. The crystal came out from Tris-HCl buffer with > peg600, and protein buffer contains sodium-phosphate. > > Does anyone figure out what this density can be ? > Thanks for any help you can give. > > Cédric
