6C4C:
reference: The Nitro Group as a Masked Electrophile in Covalent Enzyme Inhibition., Ray S, Kreitler DF, Gulick AM, Murkin AS, ACS Chem Biol. 2018 May 23. doi: 10.1021/acschembio.8b00225. PMID: 29782144

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