Hello!
I am working on a structure that has continuous density from a Lys Nz
atom to a Cys Sg; these are ~2.9A from each other. I would consider
this a H-bond; however, the 2fo-fc density does not run straight from
atom to atom in this 1.9A structure. At an apx right angle, with the
line joining these two atoms being the hypotenuse, there is aspherical
fo-fc density ~2.1A from the Cys Sg and ~1.7A from the Lys Nz as if
another atom sits between these two atoms. The modeled side chains
fit the density very well. No other atoms are close by to be ligands
so I ruled out an ion.
I'd appreciate any thoughts any of you may have...thanks!
John Horton
Emory University
