1R3G:
reference: 2'-O-[2-(Guanidinium)ethyl]-Modified Oligonucleotides: Stabilizing Effect on Duplex and Triplex Structures., Prakash TP, Puschl A, Lesnik E, Mohan V, Tereshko V, Egli M, Manoharan M, Org Lett 2004 Jun 10;6(12):1971-1974. PMID: 15176796

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