3BKF:
reference: Structural Basis of the Metal Specificity for Nickel Regulatory Protein NikR(,)., Phillips CM, Schreiter ER, Guo Y, Wang SC, Zamble DB, Drennan CL, Biochemistry. 2008 Feb 19;47(7):1938-46. Epub 2008 Jan 15. PMID: 18193897

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