3E3K:
reference: Structural Characterization of a Putative Endogenous Metal Chelator in the Periplasmic Nickel Transporter NikA., Cherrier MV, Cavazza C, Bochot C, Lemaire D, Fontecilla-Camps JC, Biochemistry. 2008 Sep 23;47(38):9937-9943. Epub 2008 Aug 30. PMID: 18759453

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