5XF9:
reference: Structural basis of the redox switches in the NAD+-reducing soluble [NiFe]-hydrogenase., Shomura Y, Taketa M, Nakashima H, Tai H, Nakagawa H, Ikeda Y, Ishii M, Igarashi Y, Nishihara H, Yoon KS, Ogo S, Hirota S, Higuchi Y, Science. 2017 Sep 1;357(6354):928-932. doi: 10.1126/science.aan4497. PMID: 28860386

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