4U2W:
reference: Atomic resolution crystal structure of HV-BBI protease inhibitor from amphibian skin in complex with bovine trypsin., Grudnik P, Debowski D, Legowska A, Malicki S, Golik P, Karna N, Rolka K, Dubin G, Proteins. 2014 Dec 24. doi: 10.1002/prot.24750. PMID: 25546528

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