1JTK:
reference: Crystal structure of the tetrameric cytidine deaminase from Bacillus subtilis at 2.0 A resolution., Johansson E, Mejlhede N, Neuhard J, Larsen S, Biochemistry 2002 Feb 26;41(8):2563-70. PMID: 11851403

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