title: Tracing the interstitial carbide of the nitrogenase cofactor during substrate turnover.
abstract: The fate of the interstitial atom of the nitrogenase cofactor during substrate turnover has remained a topic of interest since the discovery of this atom more than a decade ago. In this study, we labeled the interstitial carbide atom with (14)C and (13)C isotopes and traced the fate of the isotope under turnover conditions. Our results show that the interstitial carbide cannot be exchanged upon turnover, nor can it be used as a substrate and incorporated into the products. These observations point to a role of the interstitial carbide in stabilizing the cofactor structure, although a function of this atom in indirectly modulating the reactivity of the cofactor or directly interacting with the substrate cannot be excluded.
authors.affiliation: Department of Molecular Biology and Biochemistry, University of California, Irvine , California 92697-3900, United States.
authors.forename: Jared A
authors.initials: JA
authors.lastname: Wiig
authors.forename: Chi Chung
authors.initials: CC
authors.lastname: Lee
authors.forename: Yilin
authors.initials: Y
authors.lastname: Hu
authors.forename: Markus W
authors.initials: MW
authors.lastname: Ribbe
mesh_terms: D017554:Carbon Compounds, Inorganic / Q000737:chemistry*; D002248:Carbon Monoxide / Q000737:chemistry; D003067:Coenzymes / Q000737:chemistry*; D008401:Gas Chromatography-Mass Spectrometry; D008958:Models, Molecular; D008982:Molybdenum / Q000737:chemistry*; D009591:Nitrogenase / Q000737:chemistry*; D010084:Oxidation-Reduction; D013379:Substrate Specificity
chemical_list: D017554:Carbon Compounds, Inorganic; D003067:Coenzymes; D002248:Carbon Monoxide; D008982:Molybdenum; D009591:Nitrogenase