Calcium likes to form octahedral complexes with water (or other oxygen-containing) ligands. This looks like a classic example.
After you model and refine this, you’ll want to check water-metal distances, to make sure they are appropriate for calcium. There is a nice literature on such things, which I of course don’t have at my fingertips; but I think Wladek Minor has done some data-mining in metal-containing protein structures, and Amy Katz and Jenny Glusker have a number of papers that are relevant. There are more, of course—a little time in the “library” is warranted. Cheers, Pat Loll > On 6 Mar 2018, at 5:19 PM, Rajesh Kumar <rajesh.p...@gmail.com> wrote: > > Dear All, > > Have you had experience with this kind of density? I am wandering what this > could be? > > Thank you very much for the help. > > -Rajesh > > > <Screen Shot 2018-03-06 at 5.15.20 PM.png> > --------------------------------------------------------------------------------------- Patrick J. Loll, Ph. D. Professor of Biochemistry & Molecular Biology Drexel University College of Medicine Room 10-102 New College Building 245 N. 15th St., Mailstop 497 Philadelphia, PA 19102-1192 USA (215) 762-7706 pjl...@gmail.com pj...@drexel.edu
