Exploring the Role of the Central Carbide of the Nitrogenase Active-Site FeMo-cofactor through Targeted ¹³C Labeling and ENDOR Spectroscopy.

ABSTRACT: Mo-dependent nitrogenase is a major contributor to global biological N₂ reduction, which sustains life on Earth. Its multi-metallic active-site FeMo-cofactor (Fe₇MoS₉C-homocitrate) contains a carbide (C^4-) centered within a trigonal prismatic CFe₆ core resembling the structural motif of the iron carbide, cementite. The role of the carbide in FeMo-cofactor binding and activation of substrates and inhibitors is unknown. To explore this role, the carbide has been in effect selectively enriched with ¹³C, which enables its detailed examination by ENDOR/ESEEM spectroscopies. ¹³C-carbide ENDOR of the S = 3/2 resting state (E₀) is remarkable, with an extremely small isotropic hyperfine coupling constant,

SUBMITTER: Perez-Gonzalez A 

PROVIDER: S-EPMC9514325 | biostudies-literature | 2021 Jun

REPOSITORIES: biostudies-literature