1P25:
reference: Cobalt(II), nickel(II) and zinc(II) do not bind to intra-helical N(7) guanine positions in the B-form crystal structure of d(GGCGCC)., Labiuk SL, Delbaere LT, Lee JS, J Biol Inorg Chem 2003 Sep;8(7):715-20. Epub 2003 Jul 9. PMID: 14505075

This OCA Structure page
uses Jmol, developed by the Jmol Development Team (documentation).