I think it could be zinc ion. On Fri, Apr 30, 2010 at 5:38 AM, Daniel Bonsor <[email protected]> wrote:
> Hello again > > I currently have some unexplained density in my structure. As you can > hopefully see from the images (see file), the density is dumbbell shaped. > Whatever it is, it is coordinated by Asp and Glu residues. To me it looks > like each lobe is a ring structure. > > > The crystallization condition was: > 6.5% PEG 8K, 10mM ZnSO4, 100mM sodium cacodylate pH 6.5, 100mM Am2SO4, 1% > glycerol, with 20% glycerol as cryo. > Protein was originally in 50mM Tris, 50mM NaCl pH 7.5. > > > I originally placed a single Zn at the center of each lobe. Though after > refmac, the Zn was displaced to one side. Two zincs in each dumbbell may > have worked, but I am dubious about two zinc atoms being 4A apart and there > is still some unexplained density. Are there any possible cyclization > reactions of Tris, cacodylate or glycerol may have undergone to explain the > density? Or is it simply a highly ordered water network? Or is there some > other explanation? > > Thanks in advance > > Dan > -- Best regards, Xianhui
