4ID8:
reference: The structure of a novel electron-transfer ferredoxin from Rhodopseudomonas palustris HaA2 which contains a histidine residue in its iron-sulfur cluster-binding motif., Zhang T, Zhang A, Bell SG, Wong LL, Zhou W, Acta Crystallogr D Biol Crystallogr. 2014 May;70(Pt 5):1453-64. doi:, 10.1107/S139900471400474X. Epub 2014 Apr 30. PMID: 24816113

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