1GU6:
reference: Structure and spectroscopy of the periplasmic cytochrome c nitrite reductase from Escherichia coli., Bamford VA, Angove HC, Seward HE, Thomson AJ, Cole JA, Butt JN, Hemmings AM, Richardson DJ, Biochemistry 2002 Mar 5;41(9):2921-31. PMID: 11863430

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