title: Structural identification of iron-sulfur clusters of the respiratory chain-linked NADH dehydrogenase.
abstract: The structural nature of the iron-sulfur clusters of NADH dehydrogenase from beef heart mitochondria has been studied by the cluster extrusion technique. Enzyme samples were unfolded anaerobically in 80% (v/v) hexamethylphosphoramide/aqueous buffer in the presence of o-xylyl-alpha,alpha'-dithiol as the displacing agent and the extruded clusters were then reacted with p-trifluoromethylbenzenethiol and analyzed by Fourier transform 19F NMR at 339 MHz. Whenever extrusion was nearly complete, both binuclear and tetranuclear clusters were found at a mole ratio of approximately 2:1. Thus, the dehydrogenase, with 16 g atoms of non-heme iron present/mol of FMN, contains most likely four [2Fe-2S] and two [4Fe-4S] clusters. Because the enzyme contains four or, at the most five, EPR-detectable iron-sulfur centers, it appears that one or more of the clusters are EPR-silent.
mesh_terms: D000693:Anaerobiosis; D000818:Animals; D002417:Cattle; D003579:Cytochrome Reductases / Q000378:metabolism*; D005486:Flavin Mononucleotide / Q000032:analysis; D005583:Fourier Analysis; D006418:Heme / Q000032:analysis; D007501:Iron / Q000032:analysis; D007506:Iron-Sulfur Proteins / Q000378:metabolism*; D046911:Macromolecular Substances; D009682:Magnetic Resonance Spectroscopy; D008667:Metalloproteins / Q000378:metabolism*; D008929:Mitochondria, Heart / Q000201:enzymology*; D009245:NADH Dehydrogenase / Q000378:metabolism*; D011487:Protein Conformation; D013053:Spectrophotometry; D013455:Sulfur / Q000032:analysis
chemical_list: D007506:Iron-Sulfur Proteins; D046911:Macromolecular Substances; D008667:Metalloproteins; D006418:Heme; D013455:Sulfur; D005486:Flavin Mononucleotide; D007501:Iron; D003579:Cytochrome Reductases; D009245:NADH Dehydrogenase