4JE9:
reference: In Vitro and Cellular Self-Assembly of a Zn-Binding Protein Cryptand via Templated Disulfide Bonds., Medina-Morales A, Perez A, Brodin JD, Tezcan FA, J Am Chem Soc. 2013 Aug 14;135(32):12013-22. doi: 10.1021/ja405318d. Epub 2013, Aug 1. PMID: 23905754

This OCA Structure page
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