7JMA:
reference: Crystallographic analysis of NifB with a full complement of clusters: Structural insights into the radical SAM-dependent carbide insertion during nitrogenase cofactor assembly., Kang W, Rettberg L, Stiebritz M, Jasniewski A, Tanifuji K, Lee CC, Ribbe MW, Hu Y, Angew Chem Int Ed Engl. 2020 Oct 9. doi: 10.1002/anie.202011367. PMID: 33035363

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