title: The cyanide ligands of [FeFe] hydrogenase: pulse EPR studies of (13)C and (15)N-labeled H-cluster.
abstract: The two cyanide ligands in the assembled cluster of [FeFe] hydrogenase originate from exogenous l-tyrosine. Using selectively labeled tyrosine substrates, the cyanides were isotopically labeled via a recently developed in vitro maturation procedure allowing advanced electron paramagnetic resonance techniques to probe the electronic structure of the catalytic core of the enzyme. The ratio of the isotropic (13)C hyperfine interactions for the two CN(-) ligands-a reporter of spin density on their respective coordinating iron ions-collapses from ≈5.8 for the Hox form of hydrogenase to <2 for the CO-inhibited form. Additionally, when the maturation was carried out using [(15)N]-tyrosine, no features previously ascribed to the nitrogen of the bridging dithiolate ligand were observed suggesting that this bridge is not sourced from tyrosine.
authors.affiliation: Department of Chemistry, University of California, Davis , Davis, California 95616 United States.
authors.forename: William K
authors.initials: WK
authors.lastname: Myers
authors.forename: Troy A
authors.initials: TA
authors.lastname: Stich
authors.forename: Daniel L M
authors.initials: DL
authors.lastname: Suess
authors.forename: Jon M
authors.initials: JM
authors.lastname: Kuchenreuther
authors.forename: James R
authors.initials: JR
authors.lastname: Swartz
authors.forename: R David
authors.initials: RD
authors.lastname: Britt
mesh_terms: D003486:Cyanides / Q000737:chemistry; D045285:Desulfovibrio desulfuricans / Q000737:chemistry / Q000201:enzymology*; D004578:Electron Spin Resonance Spectroscopy; D006864:Hydrogenase / Q000737:chemistry*; D007506:Iron-Sulfur Proteins / Q000737:chemistry*; D008024:Ligands
chemical_list: D003486:Cyanides; D007506:Iron-Sulfur Proteins; D008024:Ligands; D006864:Hydrogenase