5OPH:
reference: NMR structure of a G-quadruplex formed by four d(G4C2) repeats: insights into structural polymorphism., Brcic J, Plavec J, Nucleic Acids Res. 2018 Oct 2. pii: 5114260. doi: 10.1093/nar/gky886. PMID: 30277522

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