1KV7:
reference: Crystal structure and electron transfer kinetics of CueO, a multicopper oxidase required for copper homeostasis in Escherichia coli., Roberts SA, Weichsel A, Grass G, Thakali K, Hazzard JT, Tollin G, Rensing C, Montfort WR, Proc Natl Acad Sci U S A 2002 Mar 5;99(5):2766-71. PMID: 11867755

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