Ed, Is there any chance that you might have ethylene glycol present in the condition? If so, that might work.
Sincerely, Harkewal Singh On Jul 7, 2013, at 3:21 PM, Edward A. Berry wrote: > In a structure I'm refining, there are a couple of oblong blobs associated > with carboxylates. > (screenshots at http://sb20.lbl.gov/berry/ccp4/azide/) > If I modeled with two waters, they refine too close together for normal > H-bond, > 2.3 to 2.5 A; and their density is connected. > > I considered one water with alternate locations, but the distal position > wouldn't > make much sense if the proximal water wasn't there. The density is the right > size > for azide, which was present in the medium, but I expect a chemist would find > it > unreasonable to have anionic azide (pKa of hydrazoic acid ~4.6) associating > with > a carboxylate. > Would that make sense? or does anyone have other suggestions? > (resolution is 2.2A, contour 0.25 e/A^3 or about 1.3 sigma) > > Thanks, > Ed
