On Fri, Apr 6, 2012 at 7:06 AM, Jeff Headd <jjheadd at lbl.gov> wrote: > Determining the protonation state of a HIS residue based on the diffraction > data would require very high resolution data (below 1.0A), if that is > possible at all. Or neutron diffraction (which doesn't require atomic resolution), for the people who really care. -Nat