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

22 revertants of Saccharomyces cerevisiae with intragenic suppressors (supa) of cob exon mutations (G. Burger, Mol. Gen. Genet., in the press) were analyzed. They display either a reduced amount of cytochrome b, or a shifted maximum absorption wavelength of total cytochrome b or a reduced growth rate on glycerol. The relationship of physico-chemical properties (content, light absorption and midpoint potential of cytochromes bK and bT) and functional properties (electron transport and energy yield) has been examined. In seven of eight revertants with a shifted maximum absorption wavelength of cytochrome b neither growth rate nor electron transfer activity was affected. In 13 of 14 revertants, reduced content of cytochrome b corresponds to a reduced electron transport rate through the cytochrome bc1 segment. A lower enzymatic activity, which is not due to a quantitative but to a qualitative alteration of cytochrome b was found in two revertants. Two revertants show electron transport rates of wild-type level concomitant with a reduced growth rate on glycerol, obviously due to a less efficient energy coupling. All revertants were shown to contain a high and a low potential cytochrome b, referred to as bK and bT. Those cob-/supa mutations which shift the maximum absorption wavelength or diminish the content of cytochrome b affect both b cytochromes in all cases. The results support that electron transport and energy conservation are catalyzed by the unity of cytochrome bK and bT and that both heme centers are bound to an identical apoenzyme. Comparing electron flow rates of succinate:cytochrome c oxidoreductase and NADH:cytochrome c oxidoreductase in cob- mutants and two revertants provides evidence that ubiquinone does not constitute a homogeneous pool, suggested by the dissimilar interaction of both dehydrogenases with the bc1 segment.
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PMID:Cytochrome b of cob revertants in yeast. Bioenergetic characterization of revertants with reduced content and shifted maximum absorption wavelength of cytochrome b. 608 48

Genes coding for the 40 kilodaltons (kDa), 17-kDa, 14-kDa and 11-kDa subunits of the ubiquinol-cytochrome c reductase in yeast are present in single copies in the haploid genome. We have mapped each gene to a unique genomic environment and demonstrate that integration of cloned segments into nuclear DNA by homologous crossing-over with the endogenous gene results in the replacement of the corresponding chromosomal restriction fragment by fragments of predicted sizes. Chromosomal mapping, carried out by the procedure of Falco and Botstein 1983, indicates that the gene for the 17-kDa subunit lies on chromosome VI and that for the 11-kDa subunit on chromosome XII.
Mol Gen Genet 1984
PMID:Nuclear genes coding for four subunits of the yeast ubiquinol-cytochrome c reductase complex are present in single copies in the haploid genome and at least two of these are located on different chromosomes. 609 92

The bactericidal activity of Tinopal AN [1,1-bis(3,N-5-dimethyl-benzoxazol-2-yl)-methine p-toluene sulphonate] was shown to be due to a mechanism entirely independent of its inhibitory effects upon NADH dehydrogenase which were reported previously. Whereas the compound had no significant effect upon DNA synthesis in Escherichia coli D22, RNA and protein synthesis were immediately and markedly inhibited. In confirmation, Tinopal AN caused an immediate cessation in inducible beta-galactosidase synthesis in the same organism. An in vitro assay of the transcription of calf-thymus DNA by purified E. coli RNA polymerase showed that this process was inhibited by Tinopal AN.
J Gen Microbiol 1984 Aug
PMID:The antibacterial action of Tinopal AN. 620

Genetic relations between mitochondrial mucidin-resistant locus muc3 and ubiquinol-cytochrome c reductase-deficient box loci have been studied by recombination and petite deletion analysis. It was found that the locus muc3 maps in the segment of mitochondrial DNA corresponding to the locus box2. The results suggest the participation of box2/muc3 locus in the sequences of the structural gene for cytochrome b.
Mol Gen Genet 1980
PMID:Localization of mucidin-resistant locus muc3 on mitochondrial DNA with respect to ubiquinol-cytochrome c reductase deficient box loci. Locus muc3 is allelic to box2. 625 5

Myxothiazol, an antibiotic from Myxococcus fulvus, which inhibits mitochondrial respiration in the bc1 complex of the respiratory chain, has effects on the redox components of isolated succinate-cytochrome c reductase complex which suggest that it interacts with both cytochrome b and the iron-sulfur protein of the bc1 complex. The inhibitor appears to increase the midpoint potentials of cytochromes b-562 and b-566, as indicated by an increase in their reducibility by the succinate/fumarate couple. It also causes a red shift in the optical spectrum of ferrocytochrome b-566, as reported previously (Becker, W. F., Von Jagow , G., Anke , T., Steglisch , W. (1981) FEBS Lett. 132, 329-333). This red shift is enhanced by Triton X-100, and there is no shift in the spectrum of b-562. These results are consistent with evidence that mutations conferring myxothiazol resistance in yeast map to the mitochondrial gene for cytochrome b ( Thierbach , G., and Michaelis, G. (1982) Mol. Gen. Genet. 186, 501-506). In addition, myxothiazol has effects on reduction of the cytochromes b and c1 by succinate or ubiquinol which are identical to those caused by removal of the iron-sulfur protein from the bc1 complex. It blocks reduction of cytochrome c1 during single and multiple turnovers of the bc1 complex, but does not block reduction of the b cytochromes. In the presence of antimycin, it blocks reduction of both cytochromes b and c1. In contrast to antimycin, myxothiazol inhibits oxidant-induced reduction of both b cytochromes and does not inhibit their oxidation by fumarate. Myxothiazol also inhibits reduction of the iron-sulfur protein by ubiquinol and shifts the gx resonance in the EPR spectrum of the iron-sulfur protein from g = 1.79 to 1.76. It does not affect the midpoint potential of the iron-sulfur protein, but does eliminate the increase in midpoint potential which is caused by inhibitory hydroxyquinones which bind to the iron-sulfur protein. The effects of myxothiazol are consistent with a protonmotive Q cycle pathway of electron transfer in which myxothiazol binds to cytochrome b and displaces quinone from the iron-sulfur protein of the bc1 complex. These results suggest either that a myxothiazol-induced conformational change in cytochrome b is transmitted to a quinone binding site on the iron-sulfur protein, or that there is a quinone binding site which consists of peptide domains from both cytochrome b and iron-sulfur protein.
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PMID:An inhibitor of mitochondrial respiration which binds to cytochrome b and displaces quinone from the iron-sulfur protein of the cytochrome bc1 complex. 632 77

Repeated administration of trichloroethylene (TCE) to mice by either i.p. injection or by inhalation increased the activity of hepatic microsomal NADPH cytochrome-c reductase. The NADPH cytochrome c reductase activity in microsomes isolated from lungs of animals treated with TCE by inhalation was decreased relative to controls (untreated animals). TCE inhalation was associated with pathologic changes in lungs, but not in livers of the treated animals. The duration of exposure is probably an important factor however, since animals exposed for only 1 hr per day exhibited neither pathologic changes in the lungs nor an alteration of enzyme activity. These findings indicate that inhalation of TCE, without prior treatment with inducers, can enhance activity of the hepatic mixed function oxidase system. The reduced activity of the pulmonary mixed function oxidase system in animals that inhaled TCE may reflect injury to the lungs.
Gen Pharmacol 1984
PMID:Some effects of trichloroethylene on mouse lungs and livers. 642 11

The long term effects of phenytoin administration on mixed function oxidase activities and serum estradiol in female rats were examined. No induction of hepatic mixed function oxidases was seen until 8 days after the administration of 100 mg phenytoin/kg/day either orally or intraperitoneally. Maximum increase in aniline hydroxylase, aryl hydrocarbon hydroxylase (AHH) and ethylmorphine-N-deethylase activities occurred between days 8 and 16 of treatment and decreased thereafter. No induction of lung or intestinal AHH activity was observed. Serum levels of estradiol were significantly decreased after 16 days of phenytoin treatment. Maximal increases in hepatic cytochrome P-450 and cytochrome c reductase occurred after 8-16 days of treatment. Furthermore, pentobarbital sleeping times were shortest after 16 days of phenytoin administration. The activities of all enzymes after 32 days of phenytoin treatment were less than at the peak activities at 8-16 days.
Gen Pharmacol 1984
PMID:Chronic phenytoin administration and the hepatic mixed function oxidase system in female rats. 671 46

It is shown that the Notch8 deficiency in Drosophila melanogaster affects a number of enzyme activities localized in the mitochondria, such as NADH oxidase (activity of the complete respiratory chain), NADH dehydrogenase (the first step in the respiratory chain before transfer to ubiquinone), Succinate dehydrogenase and alpha-glycerophosphate dehydrogenase. The experiments reported here do not exclude the possibility of involvement of other genes in the deficiency. The effect of duplications of the Notch locus on NADH oxidase and NADH dehydrogenase suggest that the locus determines the enzyme activities. The dosage effects of the Notch locus on activity suggest that this locus contains the structural genes for these enzymes.
Mol Gen Genet 1981
PMID:The action of the notch locus in Drosophila melanogaster. I. Effects of the notch8 deficiency on mitochondrial enzymes. 679 Sep 11

Six mutant strains (301, 102, 203, 104, 305, and 307) affected in their nitrate assimilation capability and their corresponding parental wild-type strains (6145c and 21gr) from Chlamydomonas reinhardii have been studied on different nitrogen sources with respect to NAD(P)H-nitrate reductase and its associated activities (NAD(P)H-cytochrome c reductase and reduced benzyl viologen-nitrate reductase) and to nitrite reductase activity. The mutant strains lack NAD(P)H-nitrate reductase activity in all the nitrogen sources. Mutants 301, 102, 104, and 307 have only NAD(P)H-cytochrome c reductase activity whereas mutant 305 solely has reduced benzyl viologen-nitrate reductase activity. Both activities are repressible by ammonia but, in contrast to the nitrate reductase complex of wild-type strains, require neither nitrate nor nitrite for their induction. Moreover, the enzyme from mutant 305 is always obtained in active form whereas nitrate reductase from wild-types needs to be reactivated previously with ferricyanide to be fully detected. Wild-type strains and mutants 301, 102, 104, and 307, when properly induced, exhibit an NAD(P)H-cytochrome c reductase distinguishable electrophoretically from constitutive diaphorases as a rapidly migrating band. Nitrite reductase from wild-type and mutant strains is also repressible by ammonia and does not require nitrate or nitrite for its synthesis. These facts are explained in terms of a regulation of nitrate reductase synthesis by the enzyme itself.
Mol Gen Genet 1982
PMID:Regulation of the nitrate-reducing system enzymes in wild-type and mutant strains of Chlamydomonas reinhardii. 681 63

A pseudogene, psi nad7, which has significant sequence similarity (66.7% amino acid identity) with the bovine nuclear gene for a 49 kDa subunit of the NADH dehydrogenase (NADH:ubiquinone oxidoreductase, EC 1.6.99.3), has been identified on the mitochondrial genome of the liverwort Marchantia polymorpha. The predicted coding region, which includes six termination codons, is actively transcribed into RNA molecules of 16 and 9.6 kb in length, but RNA splicing products were not detected in the liverwort mitochondria. Genomic DNA blot analysis and RNA blot analysis using poly(A)+ RNA suggest that a structurally related nuclear gene encodes the mitochondrial ND7 polypeptide. These results imply that this psi nad7 is a relic of a gene transfer event from the mitochondrial genome into the nuclear genome during mitochondrial evolution in M. polymorpha.
Mol Gen Genet 1995 Jun 10
PMID:Active transcription of the pseudogene for subunit 7 of the NADH dehydrogenase in Marchantia polymorpha mitochondria. 760 35


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