Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:1.6.99.3 (diaphorase)
 5,903 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Preparations of NADH-ubiquinone reductase from bovine heart mitochondria (Complex I) were shown to contain at least 16 polypeptides by gel electrophoresis in the presence of sodium dodecyl sulphate. 2. High-molecular-weight soluble NADH dehydrogenase prepared from Triton X-100 extracts of submitochondrial particles [Baugh & King (1972) Biochem. Biophys. Res. Commun. 49, 1165-1173] was similar to Complex I in its polypeptide composition. 3. Solubilization of Complex I by phospholipase A treatment and subsequent sucrose-density-gradient centrifugation did not alter the polypeptide composition. 4. Lysophosphatidylcholine treatment of Complex I caused some selective solubilization of a polypeptide of mol.wt. 33000 previosuly postulated to be the transmembrane component of Complex I in the mitochondrial membrane [Ragan (1975) in Energy Transducing Membranes: Structure, Function and Reconstitution (Bennun, Bacila & Najjar, eds.), Junk, The Hague, in the press]. 5. Chaotropic resolution of Complex I caused solubilization of polypeptides of molecular weights 75000, 53000, 29000, 26000 and 15500 and traces of others in the 10000-20000-mol.wt.range. 6. The major components of the iron-protein fraction from chaotropic resolution had molecular weights of 75000, 53000 and 29000, whereas the flavoprotein contained polypeptides of molecular weights 53000 and 26000 in a 1:1 molar ratio. 7. Iodination of Complex I by lactoperoxidase indicated that the water-soluble polypeptides released by chaotropic resolution, in particular those of the flavoprotein fraction, were largely buried in the intact Complex. 8. The polypeptides of molecular weights 75000, 53000, 42000, 39000, 33000, 29000 and 26000 were present in 1:2:1:1:1:1:1 molar proportions. The two subunits of molecular weight 53000 are probably non-identical.
 ...
PMID:The structure and subunit composition of the particulate NADH-ubiquinone reductase of bovine heart mitochondria. 18 Sep 73

Iodination of horse cytochrome c with the lactoperoxidase-hydrogen peroxide-iodide system results initially in the formation of the monoiodotyrosyl 74 derivative. This singly modified protein was obtained in pure form by ion exchange chromatography and preparative column electrophoresis. It shows an intact 695 nm absorption band, the midpoint potential of the native protein, a nuclear magnetic resonance spectrum which indicates an undisturbed heme crevice structure, a normal reaction with antibodies directed against native horse cytochrome c, and circular dichroic spectra in which the only changes from those of the native protein can be ascribed to the spectral properties of iodotyrosine itself. This conformationally intact derivative reacts with the succinate-cytochrome c reductase and the cytochrome c oxidase systems of beef mitochondrial particle preparations indistinguishably from the unmodified protein, showing that the region including tyrosine 74 is not involved in these enzymic electron transfer functions of the protein. The circular dichroic spectra of this derivative indicate that the minima observed at 288 and 282 nm in the spectrum of native ferricytochrome c originate from tyrosyl residue 74.
 ...
PMID:Lactoperoxidase-catalyzed iodination of horse cytochrome c:monoiodotyrosyl 74 cytochrome c. 19 98

The apical and basal-lateral plasma membranes of toad bladder epithelium were radio-iodinated with the glucose-glucose oxidase-lactoperoxidase system. The covalently bound radio iodine was used as a marker during subcellular fractionation and membrane isolation. Homogenization conditions that ensured rupture of more than 80% of the cells without substantial nuclear damage were defined by Normarski optics. The nuclei were separated by differential centrifugation and the apical and basal-lateral components were resolved by differential and sucrose density gradient centrifugation. The apical components yielded two radioactive bands that were identified as glycocalyx and plasma membrane labeled with 125I. The basal-lateral components yielded a hetero-disperse pattern made up of at least 3 radioactive bands, but the bulk of the activity of ouabain-sensitive ATPase comigrated with only one of these bands. The mitochondia, identified by assays for cytochrome oxidase and NADH cytochrome c reductase activities, were separated from the radio-iodine labeled by centrifugation in sucrose density gradients under isokinetic conditions. The labeled glycocalyx and the slowly migrating components of basal-lateral labeling were separated from the radio-iodinated membranes by centrifugation at 100,000 x g x 1 hr after removal of the mitochrondria by the isokinetic method. The labeled membranes were then subjected to ultracentrifugation in sucrose density gradients under isopycnic conditions; the basal-lateral membranes containing ouabain-sensitive ATP-ase were well resolved from the apical membranes by this method. These results provide a relatively rapid method of attaining partial purification of the apical and basal-lateral plasma membranes of toad bladder epithelium.
 ...
PMID:Isolation of radio-iodinated apical and basal-lateral plasma membranes of toad bladder epithelium. 22 11

Lactoperoxidase-catalyzed radioiodination was used to study the arrangement of the component peptides of succinate-cytochrome c reductase with respect to the aqueous phases on each side of the mitochondrial inner membrane. Mitochondria depleted of their outer membrane and inside-out vesicles purified from submitochondrial particles by the lectin-affinity procedure (D'Souza, M. P., and Lindsay, J. G. (1981) Biochim. Biophys. Acta 640, 463-472) were iodinated using immobilized preparations of lactoperoxidase. The labeled membranes were solubilized in detergent and the succinate-cytochrome c reductase was purified by immunoprecipitation with specific IgG. Analysis of the radioiodine distribution after sodium dodecyl sulfate-polyacrylamide gel electrophoresis and comparison with peptide stain patterns show that bands 2 (64 kilodaltons), 6 (30 kilodaltons), 9 (15 kilodaltons), and 11 (less than 10 kilodaltons) are labeled from the cytoplasmic surface of the membrane. Bands 1 (72 kilodaltons), 4 (48 kilodaltons), and 8 (20 kilodaltons) appear to be labeled on the matrix side of the membrane, while bands 3 (52 kilodaltons), 5 (35 kilodaltons), 7 (25 kilodaltons), and 10 (11 kilodaltons) are labeled from both sides of the membrane. Tentative identification of the labeled bands suggests that band 1 is the large subunit of succinate dehydrogenase. Bands 3 and 4 represent proteins which have been referred to as core proteins I and II. Bands 5 and 6 are the proteins associated with cytochromes b and c1, respectively; band 7 is the Rieske iron-sulfur protein.
 ...
PMID:Labeling of succinate-cytochrome c reductase with 125I. Accessibility of the peptides to the aqueous phases on the cytosolic and matrix sides of the mitochondrial membrane. 628 97

The organization of the constituent polypeptides of mitochondrial NADH dehydrogenase was studied by using two membrane-impermeable probes, diazobenzene[35S]sulphonate and lactoperoxidase-catalysed radioiodination. The incorporation of label into the subunits of the isolated enzyme was compared with that obtained with enzyme immunoprecipitated from labelled mitochondria or inverted submitochondrial particles. On the basis of accessibility to these two labels, we divide the polypeptides of Complex I into five groups: those that are apparently buried in the enzyme, those that are accessible to labelling in the isolated enzyme but not in the membrane, those that are exposed on the cytoplasmic face of the membrane, those that are exposed on the matrix face and finally those that are exposed on both faces and are therefore transmembranous. We conclude that NADH dehydrogenase is asymmetrically organized across the inner mitochondrial membrane.
 ...
PMID:The organization of NADH dehydrogenase polypeptides in the inner mitochondrial membrane. 739 18

Dihydrolipoamide dehydrogenase (LADH) lipoamide reductase activity decreased whereas enzyme diaphorase activity increased after LADH treatment with myeloperoxidase (MPO) dependent systems (MPO/H2O2/halide, MPO/NADH/halide and MPO/H2O2/nitrite systems. LADH inactivation was a function of the composition of the inactivating system and the incubation time. Chloride, iodide, bromide, and the thiocyanate anions were effective complements of the MPO/H2O2 system. NaOCl inactivated LADH, thus supporting hypochlorous acid (HOCl) as putative agent of the MPO/H2O2/NaCl system. NaOCl and the MPO/H2O2/NaCl system oxidized LADH thiols and NaOCl also oxidized LADH methionine and tyrosine residues. LADH inactivation by the MPO/NADH/halide systems was prevented by catalase and enhanced by superoxide dismutase, in close agreement with H2O2 production by the LADH/NADH system. Similar effects were obtained with lactoperoxidase and horse-radish peroxidase supplemented systems. L-cysteine, N-acetylcysteine, penicillamine, N-(2-mercaptopropionylglycine), Captopril and taurine protected LADH against MPO systems and NaOCl. The effect of the MPO/H2O2/NaNO2 system was prevented by MPO inhibitors (sodium azide, isoniazid, salicylhydroxamic acid) and also by L-cysteine, L-methionine, L-tryptophan, L-tyrosine, L-histidine and reduced glutathione. The summarized observations support the hypothesis that peroxidase-generated "reactive species" oxidize essential thiol groups at LADH catalytic site.
 ...
PMID:Inactivation of myocardial dihydrolipoamide dehydrogenase by myeloperoxidase systems: effect of halides, nitrite and thiol compounds. 1019 78

The aim of this work was to identify proteins specific for plant cell membranes which could then be used as unique markers. A crude membrane fraction was isolated from corn coleoptiles and separated on non-linear sucrose density gradients. Separation of endoplasmic reticulum (NADH-cytochrome c reductase), mitochondria (cytochrome c oxidase), golgi (inosine diphosphatase), and plasma membranes (N-1-naphthylphthalamic acid-binding) was achieved. The membrane proteins from the gradient fractions were separated using sodium dodecyl sulphate-poly-acrylamide gel electrophoresis and the gels stained with coomassie blue or with concanavalin A/peroxidase to detect glycoproteins. Proteins specific for the various membranes were identified. Five proteins including two glycoproteins were plasma membrane markers. Protoplasts were isolated and iodinated using lactoperoxidase/glucose oxidase covalently attached to beads. Eleven iodinated proteins were found and three of these corresponded to proteins specifically associated with plasma membranes in the density gradients. Two methods for detecting Ca(2+)-binding proteins following sodium dodecylsulphate polyacrylamide gel electrophoresis were employed. The majority of such proteins were found in the endoplasmatic reticulum and one was specific for plasma membranes. In vitro and in vivo phosphorylation of membrane proteins was examined and the majority of proteins phosphorylated were glycoproteins. Two of the phosphorylated proteins (Mr=110,000 and 20,000) were also iodinated on protoplasts and may be part of the plasma membrane ATPases.
...
PMID:Identification of specific proteins and glycoproteins associated with membrane fractions isolated from Zea mays L. coleoptiles. 2426 41