title: ESEEM studies of the iron-sulphur clusters of succinate dehydrogenase in Arum maculatum spadix mitochondrial membranes.
abstract: We have performed ESEEM spectroscopy in order to obtain structural information about the environment of the [2Fe-2S] cluster and the [3Fe-4S] cluster of succinate dehydrogenase (Centres 1 and 3, respectively) in intact Arum maculatum mitochondrial membranes. Both iron-sulphur clusters showed modulations indicative of 14N in the three-pulse echo decay envelopes. We have estimated the hyperfine couplings for the reduced [2Fe-2S] cluster (A approximately 1.1 MHz) and the oxidised [3Fe-4S] cluster (A approximately 0.8 MHz). Our results are compared with ESEEM data obtained for purified [2Fe-2S] cluster-containing proteins, namely Spirulina platensis ferredoxin, a protein for which the three-dimensional structure is known, and Escherichia coli fumarate reductase. The hyperfine and quadrupolar coupling parameters determined are consistent with a weak interaction of Centre 1 and Centre 3 with peptide 14N, rather than 14N of imidazole rings.
authors.affiliation: Centre for the Study of Metals in Biology and Medicine, King's College, London, UK.
authors.forename: J K
authors.initials: JK
authors.lastname: Shergill
authors.forename: R
authors.initials: R
authors.lastname: Cammack
mesh_terms: D004578:Electron Spin Resonance Spectroscopy / Q000379:methods*; D007425:Intracellular Membranes / Q000201:enzymology*; D007506:Iron-Sulfur Proteins / Q000032:analysis / Q000737:chemistry*; D008928:Mitochondria / Q000201:enzymology*; D010944:Plants / Q000201:enzymology*; D013385:Succinate Dehydrogenase / Q000737:chemistry*
chemical_list: D007506:Iron-Sulfur Proteins; D013385:Succinate Dehydrogenase