3LBG:
reference: Near-atomic resolution structures of urate oxidase complexed with its substrate and analogues: the protonation state of the ligand., Gabison L, Chiadmi M, El Hajji M, Castro B, Colloc'h N, Prange T, Acta Crystallogr D Biol Crystallogr. 2010 Jun;66(Pt 6):714-24. Epub 2010 May 15. PMID: 20516624

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