2AFH:
reference: Nitrogenase complexes: multiple docking sites for a nucleotide switch protein., Tezcan FA, Kaiser JT, Mustafi D, Walton MY, Howard JB, Rees DC, Science 2005 Aug 26;309(5739):1377-80. PMID: 16123301

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uses Jmol, developed by the Jmol Development Team (documentation).