Puede utilizar el filtro de búsqueda del panel izquierdo para acotar los resultados
Filtro
Tipo de publicación
Todos Libros Revistas
Título
Autor
Palabras clave
ISBN
Acceso DOI
Acceso digital CSIC
Buscar
Datos técnicos
RevistaBiochemistry
Año2011
Volumen50
Páginas5858-5869
Internacional

[NiFe] and [FeS] Cofactors in the Membrane-Bound Hydrogenase of Ralstonia eutropha Investigated by X-ray Absorption Spectroscopy: Insights into O(2)-Tolerant H(2) Cleavage

Autores:Johannes Fritsch , Simone Loescher , Oliver Sanganas , Elisabeth Siebert , Ingo Zebger , Matthias Stein , Marcus Ludwig , Antonio López de Lacey, Holger Dau , Baerbel Friedrich , Oliver Lenz , Michale Haumann
Grupos de investigación:BioElectroCatálisis
Molecular features that allow certain [NiFe] hydrogenases to catalyze the conversion of molecular hydrogen (H(2)) in the presence of dioxygen (O(2)) were investigated. Using X-ray absorption spectroscopy (XAS), we compared the [NiFe] active site and FeS clusters in the O(2)-tolerant membrane-bound hydrogenase (MBH) of Ralstonia eutropha and the O(2)-sensitive periplasmic hydrogenase (PH) of Desulfovibrio gigas. Fe-XAS indicated an unusual complement of iron-sulfur centers in the MBH, likely based on a specific structure of the FeS cluster proximal to the active site. This cluster is a [4Fe4S] cubane in PH. For MBH, it comprises less than similar to 2.7 angstrom Fe-Fe distances and additional longer vectors of >= 3.4 angstrom, consistent with an Fe trimer with a more isolated Fe ion. Ni-XAS indicated a similar architecture of the [NiFe] site in MBH and PH, featuring Ni coordination by four thiolates of conserved cysteines, i.e., in the fully reduced state (Ni-SR). For oxidized states, short Ni-mu O bonds due to Ni-Fe bridging oxygen species were detected in the Ni-B state of the MBH and in the Ni-A state of the PH. Furthermore, a bridging sulfenate (CysSO) is suggested for an inactive state (Ni(ia)-S) of the MBH. We propose that the O(2) tolerance of the MBH is mainly based on a dedicated electron donation from a modified proximal FeS cluster to the active site, which may favor formation of the rapidly reactivated Ni-B state instead of the slowly reactivated Ni-A state. Thereby, the catalytic activity of the MBH is facilitated in the presence of both H(2) and O(2).
Palabras clave:DESULFOVIBRIO-GIGAS HYDROGENASE; OXYGEN-TOLERANT HYDROGENASE; BACTERIUM AQUIFEX-AEOLICUS; NICKEL-IRON HYDROGENASE; LOW-LEVEL H-2; ACTIVE-SITE; METAL CENTERS; ELECTRONIC-STRUCTURE; FTIR SPECTROSCOPY; REDOX PROPERTIES
logo de CSIC