4NMN:
reference: Nucleotide and partner-protein control of bacterial replicative helicase structure and function., Strycharska MS, Arias-Palomo E, Lyubimov AY, Erzberger JP, O'Shea VL, Bustamante CJ, Berger JM, Mol Cell. 2013 Dec 26;52(6):844-54. doi: 10.1016/j.molcel.2013.11.016. PMID: 24373746

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