1KX4:
reference: Solvent mediated interactions in the structure of the nucleosome core particle at 1.9 a resolution., Davey CA, Sargent DF, Luger K, Maeder AW, Richmond TJ, J Mol Biol 2002 Jun 21;319(5):1097-113. PMID: 12079350

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