1BQR:
reference: Crystal structure determinations of oxidized and reduced pseudoazurins from Achromobacter cycloclastes. Concerted movement of copper site in redox forms with the rearrangement of hydrogen bond at a remote histidine., Inoue T, Nishio N, Suzuki S, Kataoka K, Kohzuma T, Kai Y, J Biol Chem. 1999 Jun 18;274(25):17845-52. PMID: 10364229

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