6V5T:
reference: 19F NMR reveals the conformational properties of free thrombin and its zymogen precursor prethrombin-2., Ruben EA, Gandhi PS, Chen Z, Koester SK, DeKoster GT, Frieden C, Di Cera E, J Biol Chem. 2020 May 1. pii: RA120.013419. doi: 10.1074/jbc.RA120.013419. PMID: 32358061

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