4D8F:
reference: Evidence That the beta Subunit of Chlamydia trachomatis Ribonucleotide Reductase Is Active with the Manganese Ion of Its Manganese(IV)/Iron(III) Cofactor in Site 1., Dassama LM, Boal AK, Krebs C, Rosenzweig AC, Bollinger JM, J Am Chem Soc. 2012 Feb 8;134(5):2520-3. Epub 2012 Jan 25. PMID: 22242660

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