1AV2:
reference: The conducting form of gramicidin A is a right-handed double-stranded double helix., Burkhart BM, Li N, Langs DA, Pangborn WA, Duax WL, Proc Natl Acad Sci U S A 1998 Oct 27;95(22):12950-5. PMID: 9789021

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