1AGA:
reference: The agarose double helix and its function in agarose gel structure., Arnott S, Fulmer A, Scott WE, Dea IC, Moorhouse R, Rees DA, J Mol Biol 1974 Dec 5;90(2):269-84. PMID: 4453017

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