2XXG:
reference: Identification of the proton channel to the active site type 2 Cu center of nitrite reductase: structural and enzymatic properties of the His254Phe and Asn90Ser mutants., Hough MA, Eady RR, Hasnain SS, Biochemistry. 2008 Dec 23;47(51):13547-53. PMID: 19053252

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