Characterization of a Mo-Nitrogenase Variant Containing a Citrate-Substituted Cofactor.

Nitrogenase converts N to NH , and CO to hydrocarbons, at its cofactor site. Herein, we report a biochemical and spectroscopic characterization of a Mo-nitrogenase variant expressed in an Azotobacter vinelandii strain containing a deletion of nifV, the gene encoding the homocitrate synthase. Designated NifDK , the catalytic component of this Mo-nitrogenase variant contains a citrate-substituted cofactor analogue.

A V-Nitrogenase Variant Containing a Citrate-Substituted Cofactor.

Nitrogenases catalyze the ambient reduction of N and CO at its cofactor site. Herein we present a biochemical and spectroscopic characterization of an Azotobacter vinelandii V nitrogenase variant expressing a citrate-substituted cofactor. Designated VnfDGK , the catalytic component of this V nitrogenase variant has an αβ (δ) subunit composition and carries an 8Fe P* cluster and a citrate-substituted V cluster analogue in the αβ dimer, as well as a 4Fe cluster in the "orphaned" β-subunit.

Structural Analysis of a Nitrogenase Iron Protein from Methanosarcina acetivorans: Implications for CO Capture by a Surface-Exposed [FeS] Cluster.

Nitrogenase iron (Fe) proteins reduce CO to CO and/or hydrocarbons under ambient conditions. Here, we report a 2.4-Å crystal structure of the Fe protein from (NifH), which is generated in the presence of a reductant, dithionite, and an alternative CO source, bicarbonate.

A Comparative Analysis of the CO-Reducing Activities of MoFe Proteins Containing Mo- and V-Nitrogenase Cofactors.

The Mo and V nitrogenases are structurally homologous yet catalytically distinct in their abilities to reduce CO to hydrocarbons. Here we report a comparative analysis of the CO-reducing activities of the Mo- and V-nitrogenase cofactors (i.e.

Tuning Electron Flux through Nitrogenase with Methanogen Iron Protein Homologues.

Nitrogenase uses a reductase component called Fe protein to deliver electrons to its catalytic partner for substrate reduction. The essential role of Fe protein in catalysis makes it an ideal target for regulating the electron flux and enzymatic activity of nitrogenase without perturbing the cofactor site. This work reports that hybrids between the Fe protein homologs of Methanosarcina acetivorans and the catalytic components of Azotobacter vinelandii can trap substrate CO through reduced electron fluxes.