title: Isolation of fumarate reductase from Desulfovibrio multispirans, a sulfate reducing bacterium.
abstract: Fumarate reductase was isolated and purified 100-fold to homogeneity from Desulfovibrio multispirans, a new species of sulfate-reducing bacteria. The enzyme contained 1 mol of non-covalently bound FAD and four subunits with Mr 45,000, 32,000, 30,000 and 27,000. EPR spectroscopy showed the existence of two iron-sulfur clusters. The absorption spectrum showed a broad region of high absorbance from 450 nm to 300 nm with a protein peak at 278 nm. The ratio of A278:A400 was 2.60. The specific activity was 110 mumoles H2/mg of protein. The Km for fumarate was 2.5 mM. The activation energy was 8.7 kcal/mol. Electron transport from H2 to fumarate in intact cells was inhibited by 2-heptyl-4-hydroxy-quinoline-N-oxide, a quinone inhibitor, indicating the participation of quinone (probably menaquinone) in fumarate reduction.
mesh_terms: D003901:Desulfovibrio / Q000201:enzymology*; D004578:Electron Spin Resonance Spectroscopy; D005415:Flavins / Q000378:metabolism; D007506:Iron-Sulfur Proteins / Q000378:metabolism; D007700:Kinetics; D046911:Macromolecular Substances; D008565:Membrane Proteins / Q000302:isolation & purification / Q000378:metabolism; D008970:Molecular Weight; D013057:Spectrum Analysis; D013385:Succinate Dehydrogenase / Q000302:isolation & purification*
chemical_list: D005415:Flavins; D007506:Iron-Sulfur Proteins; D046911:Macromolecular Substances; D008565:Membrane Proteins; D013385:Succinate Dehydrogenase