2GD4:
reference: Antithrombin-S195A factor Xa-heparin structure reveals the allosteric mechanism of antithrombin activation., Johnson DJ, Li W, Adams TE, Huntington JA, EMBO J. 2006 May 3;25(9):2029-37. Epub 2006 Apr 13. PMID: 16619025

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