1PUP:
reference: Crystal structure of a peptide nucleic acid (PNA) duplex at 1.7 A resolution., Rasmussen H, Kastrup JS, Nielsen JN, Nielsen JM, Nielsen PE, Nat Struct Biol 1997 Feb;4(2):98-101. PMID: 9033585

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