2NQN:
reference: Mutational Analysis of Escherichia coli MoeA: Two Functional Activities Map to the Active Site Cleft(,)., Nichols JD, Xiang S, Schindelin H, Rajagopalan KV, Biochemistry. 2007 Jan 9;46(1):78-86. PMID: 17198377

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