4ZRO:
reference: X-ray structure and inhibition of the feline infectious peritonitis virus 3C-like protease: Structural implications for drug design., St John SE, Therkelsen MD, Nyalapatla PR, Osswald HL, Ghosh AK, Mesecar AD, Bioorg Med Chem Lett. 2015 Nov 15;25(22):5072-7. doi: 10.1016/j.bmcl.2015.10.023., Epub 2015 Oct 13. PMID: 26592814

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