1SEK:
reference: The structure of active serpin 1K from Manduca sexta., Li J, Wang Z, Canagarajah B, Jiang H, Kanost M, Goldsmith EJ, Structure Fold Des 1999 Jan 15;7(1):103-9. PMID: 10368276

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