2KV0:
reference: 2-Aminopurine incorporation perturbs the dynamics and structure of DNA., Dallmann A, Dehmel L, Peters T, Mugge C, Griesinger C, Tuma J, Ernsting NP, Angew Chem Int Ed Engl. 2010 Aug 9;49(34):5989-92. PMID: 20632340

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