4DII:
reference: High-resolution structures of two complexes between thrombin and thrombin-binding aptamer shed light on the role of cations in the aptamer inhibitory activity., Russo Krauss I, Merlino A, Randazzo A, Novellino E, Mazzarella L, Sica F, Nucleic Acids Res. 2012 Jun 4. PMID: 22669903

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