4CCH:
reference: Structural Insights into DNA Replication without Hydrogen Bonds., Betz K, Malyshev DA, Lavergne T, Welte W, Diederichs K, Romesberg FE, Marx A, J Am Chem Soc. 2013 Nov 27. PMID: 24283923

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