1HUT:
reference: The structure of alpha-thrombin inhibited by a 15-mer single-stranded DNA aptamer., Padmanabhan K, Padmanabhan KP, Ferrara JD, Sadler JE, Tulinsky A, J Biol Chem 1993 Aug 25;268(24):17651-4. PMID: 8102368

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