High-Resolution ENDOR Spectroscopy Combined with Quantum Chemical Calculations Reveals the Structure of Nitrogenase Janus Intermediate E₄(4H).

ABSTRACT: We have shown that the key state in N₂ reduction to two NH₃ molecules by the enzyme nitrogenase is E₄(4H), the "Janus" intermediate, which has accumulated four [e^-/H⁺] and is poised to undergo reductive elimination of H₂ coupled to N₂ binding and activation. Initial ¹H and ⁹⁵Mo ENDOR studies of freeze-trapped E₄(4H) revealed that the catalytic multimetallic cluster (FeMo-co) binds two Fe-bridging hydrides, [Fe-H-Fe]. However, the analysis failed to provide a satisfactory picture of the relative spatial relationships of the two [Fe-H-Fe]. Our recent density functional theory (DFT) study yielded a lowest-energy form, denoted as E₄(4H)^(a), with two parallel Fe-H-

SUBMITTER: Hoeke V 

PROVIDER: S-EPMC6956989 | biostudies-literature | 2019 Jul

REPOSITORIES: biostudies-literature