2BZC:
reference: Protonation of a histidine copper ligand in fern plastocyanin., Hulsker R, Mery A, Thomassen EA, Ranieri A, Sola M, Verbeet MP, Kohzuma T, Ubbink M, J Am Chem Soc. 2007 Apr 11;129(14):4423-9. Epub 2007 Mar 17. PMID: 17367139

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