4WJY:
reference: Resolution of key roles for the distal pocket histidine in cytochrome C nitrite reductases., Lockwood CW, Burlat B, Cheesman MR, Kern M, Simon J, Clarke TA, Richardson DJ, Butt JN, J Am Chem Soc. 2015 Mar 4;137(8):3059-68. doi: 10.1021/ja512941j. Epub 2015 Feb, 18. PMID: 25658043

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