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. Author manuscript; available in PMC: 2018 Oct 16.
Published in final edited form as: Nat Chem. 2018 Apr 16;10(5):568–572. doi: 10.1038/s41557-018-0029-4

Figure 4. Refined model of L-cluster assembly on NifB.

Figure 4

The radical SAM-dependent carbide insertion and the concurrent 8Fe core rearrangement precede the incorporation of the ‘9th S’ at the catalytically important belt region of the nitrogenase cofactor, resulting in an L*-cluster ([Fe8S8C]) that is nearly indistinguishable from the L-cluster ([Fe8S9C]) except for the missing ‘9th S’. The encircled black asterisk represents the ‘vacant’ site of the L*-cluster, which may be occupied by a cysteine thiolate or water molecule. Color code: Fe, orange; Mo, cyan; S, yellow; C, gray; N, blue; O, red.