title: Pulsed electron-electron double resonance on multinuclear metal clusters: assignment of spin projection factors based on the dipolar interaction.
abstract: The interaction between two paramagnetic metal centers, a [3Fe-4S](+) cluster and a [NiFe] center, is investigated in the hydrogenase from Desulfovibrio vulgaris Miyazaki F by pulsed ELDOR (electron-electron double resonance). The distance between the metal centers is known from X-ray crystallography. The experimental dipolar spin-spin interaction deviates from the value expected for two point-dipoles located at the centers of the metal clusters. An extended spin-coupling model accounting for the spin coupling in the [3Fe-4S](+) cluster yields the observed interaction under the assumption of a particular magnetic coupling scheme for the three Fe ions. These results demonstrate that pulsed ELDOR can be used to gain insight into the inner structure of a multinuclear metal cluster.
authors.affiliation: Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany.
authors.forename: Celine
authors.initials: C
authors.lastname: Elsässer
authors.forename: Marc
authors.initials: M
authors.lastname: Brecht
authors.forename: Robert
authors.initials: R
authors.lastname: Bittl
mesh_terms: D003198:Computer Simulation; D016969:Desulfovibrio vulgaris / Q000201:enzymology; D004578:Electron Spin Resonance Spectroscopy; D005583:Fourier Analysis; D006859:Hydrogen / Q000737:chemistry / Q000378:metabolism; D006864:Hydrogenase / Q000737:chemistry* / Q000378:metabolism; D007506:Iron-Sulfur Proteins / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular
chemical_list: D007506:Iron-Sulfur Proteins; D006859:Hydrogen; C043296:nickel-iron hydrogenase; D006864:Hydrogenase