The interstitial atom of the nitrogenase FeMo-cofactor: ENDOR and ESEEM evidence that it is not a nitrogen. Academic Article uri icon


  • X-ray crystallographic study of the nitrogenase MoFe protein revealed electron density from an atom (denoted X) inside the active-site metal cluster, the [MoFe7S9:homocitrate] FeMo-cofactor. The electron density associated with X is consistent with a single N, O, or C atom. We now have tested whether X is an N or not by comparing the Q-band ENDOR and ESEEM signals from resting-state (S = 3/2) MoFe protein and NMF-extracted FeMo-co from bacteria grown with either 14N or 15N as the exclusive N source. All of the 14N or 15N signals associated with the protein are lost upon extraction of the FeMo-co. We interpret this as strong evidence that X is not an N.

published proceedings

  • J Am Chem Soc

author list (cited authors)

  • Yang, T., Maeser, N. K., Laryukhin, M., Lee, H., Dean, D. R., Seefeldt, L. C., & Hoffman, B. M

citation count

  • 75

complete list of authors

  • Yang, Tran-Chin||Maeser, Nathan K||Laryukhin, Mikhail||Lee, Hong-In||Dean, Dennis R||Seefeldt, Lance C||Hoffman, Brian M

publication date

  • September 2005