title: Purification and characterization of NADH dehydrogenase complex from Paracoccus denitrificans.
abstract: An NADH dehydrogenase complex was isolated from the plasma membranes of aerobically grown Paracoccus denitrificans cells by extraction with NaBr and purification on an NAD-agarose column. The NADH-ubiquinone-1 reductase activity of the isolated NADH dehydrogenase complex was about 10 times higher than that of the NaBr extract. The preparation was composed of 10 (6 major and 4 minor) unlike polypeptides, and lacked identifiable components and activities characteristic of other enzyme complexes of the oxidative phosphorylation system. The purified enzyme contained noncovalently bound FMN, nonheme iron, and acid-labile sulfide. The ratio of FMN to nonheme iron to acid-labile sulfide was 1:13 approximately 14:11 approximately 12, suggestive of the presence of multiple iron-sulfur clusters. The isolated NADH dehydrogenase complex cross-reacted with antisera to beef heart mitochondrial complex I and protein fraction derived therefrom, indicating the presence in the Paracoccus enzyme of antigenic sites similar to those in the intact complex I and its iron-sulfur protein and possibly hydrophobic protein fractions.
mesh_terms: D005486:Flavin Mononucleotide / Q000302:isolation & purification; D007120:Immunochemistry; D007501:Iron / Q000302:isolation & purification; D016660:NAD(P)H Dehydrogenase (Quinone); D010231:Paracoccus denitrificans / Q000201:enzymology* / Q000254:growth & development; D010455:Peptides / Q000302:isolation & purification; D011808:Quinone Reductases / Q000302:isolation & purification*
chemical_list: D010455:Peptides; D005486:Flavin Mononucleotide; D007501:Iron; D016660:NAD(P)H Dehydrogenase (Quinone); D011808:Quinone Reductases