Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

We have sequenced a region (7,376-bp) of the mitochondrial (mt) DNA (54 kb) of the cellular slime mold, Dictyostelium discoideum. From the DNA and amino-acid sequence comparisons with known sequences, genes for ATPase subunit 9 (ATP9), cytochrome b (CYTB), NADH dehydrogenase subunits 1, 3 and 6 (ND1, ND3 and ND6), small subunit rRNA (SSU rRNA) and seven tRNAs (Arg, Asn, Cys, Lys, f-Met, Met and Pro) have been identified. The sequenced region of the mtDNA has a high average A + T-content (70.8%). The A + T-content of protein-genes (73.6%) is considerably higher than that of RNA genes (61.3%). Even with the strong AT-bias, the genetic code employed is most probably the universal one. All seven tRNAs are able to form typical clover leaf structures. The molecular phylogenetic trees of CYTB and SSU rRNA suggest that D. discoideum is closer to green plants than to animals and fungi.
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PMID:Codon usage, genetic code and phylogeny of Dictyostelium discoideum mitochondrial DNA as deduced from a 7.3-kb region. 773 10

Cytochrome c reductase from potato comprises ten subunits with apparent molecular sizes between 55 and < 10 kDa. The subunit with the highest electrophoretic mobility on SDS-polyacrylamide gels was isolated and analysed by cyclic Edman degradation. Mixtures of degenerative oligonucleotides were derived from the obtained sequence data and used for the isolation of corresponding cDNA clones. The clones encode a protein of 72 amino acids which exhibits significant sequence identity with a 9.5 kDa subunit of cytochrome c reductase from bovine and a 11 kDa subunit of the enzyme complex from yeast. Comparison between the deduced amino acid sequence of the open reading frame and the sequence of the mature protein reveals that only the initiator methionine is absent in the functional subunit. Hence the protein has a calculated molecular mass of 8.2 kDa. Transcripts of the potato 8.2 kDa protein were not translated in reticulocyte lysates but in vitro translation worked efficiently with wheat germ lysate. Import of the radiolabelled protein into isolated mitochondria from potato seems to depend on a potential across the inner membrane and confirms the absence of a cleavable mitochondrial presequence.
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PMID:Primary structure, cell-free synthesis and mitochondrial targeting of the 8.2 kDa protein of cytochrome c reductase from potato. 780 51

Both phenylbutazon and mofebutazon inhibit oxidative fragmentation of the methionine derivative, 2-keto-4-methylthio-butyric acid (KMB) by xanthine oxidase--or diaphorase mediated OH radical production. Differentiation of the two non-steroidal antiinflammatory drugs is possible by means of determining oxygen reduction by xanthine oxidase or diaphorase in the presence of the naphthoquinone, juglone, where only mofebutazon shows an inhibitory effect.
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PMID:Antioxidative properties of phenazone derivatives: differentiation between phenylbutazon and mofebutazon. 821 10

Several mitochondrial genes from a large number of different fungi, mammals and plants have been sequenced but little is known about the corresponding translation products. We have affinity purified cytochrome c reductase from potato mitochondria and isolated the mitochondrially encoded cytochrome b protein. Amino-terminal sequencing reveals that the polypeptide does not start with a methionine. Comparison of the amino acid sequence with the recently published sequence of the gene encoding the cytochrome b apoprotein suggests that the N-formylmethionine is removed. This result provides the first evidence for the presence of a deformylase and a methionine aminopeptidase in mitochondria.
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PMID:Purification and sequencing of cytochrome b from potato reveals methionine cleavage of a mitochondrially encoded protein. 842 Jul 97

The nucleotide sequence of the regions flanking the A+T region of Drosophila melanogaster mitochondrial DNA (mtDNA) has been determined. Included are the genes encoding the transfer RNAs for valine, isoleucine, glutamine and methionine, the small ribosomal RNA and the 5'-coding sequences of the large ribosomal RNA and NADH dehydrogenase subunit II. This completes the nucleotide sequence of the D. melanogaster mitochondrial genome. The circular mtDNA of D. melanogaster varies in size among different populations largely due to length differences in the control region (Fauron & Wolstenholme, 1976; Fauron & Wolstenholme, 1980a, b); the mtDNA region we have sequenced, combined with those sequenced by others, yields a composite genome that is 19,517 bp in length as compared to 16,019 bp for the mtDNA of D. yakuba. D. melanogaster mtDNA exhibits an extreme bias in base composition; it comprises 82.2% deoxyadenylate and thymidylate residues as compared to 78.6% in D. yakuba mtDNA. All genes encoded in the mtDNA of both species are in identical locations and orientations. Nucleotide substitution analysis reveals that tRNA and rRNA genes evolve at less than half the rate of protein coding genes.
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PMID:Drosophila melanogaster mitochondrial DNA: completion of the nucleotide sequence and evolutionary comparisons. 882 64

Treatment of red cell ghosts with ozone inhibited both AChE (marking the outside of the membrane) and G3PDH (marking the inside of the membrane). There was no change in tryptophan fluorescence of the ghosts after the ozone treatment. Band 3 protein was isolated from the ozone-treated ghosts. The protein was digested with trypsin to obtain water soluble peptides from the cytoplasmic N-terminal tail and the interhelical loops. Fluorescent peptides included GWVIHPLGLR from the outer loop between helices 7 and 8, and peptide WMEAAR from the N-terminal cytoplasmic tail. Neither one of these peptides was oxidized by ozone. This was true whether or not the ghosts were sealed. We conclude that the position of these tryptophans either in the membrane structure, or because of binding to other proteins in the cytoplasmic tail, protects them from oxidation by ozone. Treatment of horse heart cytochrome c with ozone did not change the absorbance spectrum in the heme region or the tryptophan absorbing region. HPLC of the ozone-treated cytochrome c showed that cytochrome c was being modified, indicated by a change in the elution time. Treatment of cytochrome c with ozone did not change the activity in the NADH-cytochrome c reductase assay. Digestion of the ozone-treated cytochrome c with trypsin gave peptides which demonstrated normal fluorescence. (Cytochrome c has abnormally low fluorescence, which is not changed by ozone exposure.) The peptides were separated by HPLC. The fluorescence of the tryptophan-containing peptide (GITWK) was not decreased by treatment of the cytochrome c by ozone. Amino acid analysis of the ozone-treated cytochrome c indicated that methionine was oxidized. We conclude that tryptophan in cytochrome c is protected from oxidation by ozone because of the interaction with the porphyrin ring. Bovine serum albumin and human serum albumin were treated with ozone. There was a monotonic decrease in tryptophan fluorescence in both cases. Digestion of BSA with trypsin produced two fluorescent peptides. The peptide FWGK was identified by coelution with the authentic peptide. The putative peptide AWSVAR was not the same as the chemically synthesized peptide. The peptide sequences FWGK and "AWSVAR" were both oxidized in ozone-treated bovine serum albumin, with no detectable discrimination. Tryptic digestion of the ozone-treated human serum albumin produced a single fluorescent peptide, which was oxidized by ozone. The putative peptide AWAVAR in the tryptic digest of HSA was distinct from chemically synthesized peptide. The oxidation of tryptophans in proteins by ozone is markedly influenced by position in tertiary structure, position in membrane structure, and by chemical interactions within the protein.
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PMID:Reaction of ozone with protein tryptophans: band III, serum albumin, and cytochrome C. 902 65

Subunit 7 of the yeast cytochrome bc1 complex is encoded by the nuclear QCR7 gene and is essential for respiration. This protein does not contain a cleavable N-terminal mitochondrial targeting sequence, and it is not understood how the Qcr7 protein is imported into mitochondria and assembled into the complex. To test the role of the N terminus of the Qcr7 protein in mitochondrial import, assembly of the complex, and proton translocation, we inactivated the endogenous QCR7 gene and expressed mutated qcr7 genes capable of synthesizing proteins truncated by 7, 10, 14, and 20 residues (Qcr7p-delta7, Qcr7p-delta10, Qcr7p-delta14, and Qcr7p-delta20, respectively) from the N terminus. In addition, we studied two mutants containing Qcr7 proteins with point mutations in addition to a delta7 truncation, Qcr7p-delta7(D13V) and Qcr7p-delta7(R10K). All the mutant proteins with the exception of Qcr7p-delta10 were present in the mitochondria at 30 degrees C, although most at lower steady-state levels than the Qcr7p from the strain overexpressing wild type QCR7. The absence of the Qcr7p-delta10 may be the result of an unstable protein or a decrease in the efficiency of mitochondrial import due to its compromised amphipathic alpha-helix and the presence of a negative charge exposed at the N terminus. Cytochrome c reductase activities and the amounts of ATP synthesized were comparable with the wild type in the strain expressing Qcr7p-delta7. The strain expressing Qcr7p-delta7(R10K) had an identical phenotype to the one containing the Qcr7p-delta7, whereas strains expressing the Qcr7p-delta10, Qcr7p-delta14, Qcr7p-delta20, and Qcr7p-delta7(D13V) were all respiration-deficient. Examination of the steady-state levels of complex III subunits showed that core protein 2, cytochrome c1, the iron-sulfur protein, and the 11-kDa subunit are reduced in respiration-deficient mutant strains. Results from deletion analyses indicate that the N-terminal 20 residues (after Met-1) of the Qcr7 protein are not essential for import into mitochondria and that the N-terminal seven residues (after Met-1) are not involved in proton translocation. The results of this work show, however, that the N terminus of the Qcr7 protein is essential for the biosynthesis of ubiquinol-cytochrome c reductase.
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PMID:The N terminus of the Qcr7 protein of the cytochrome bc1 complex is not essential for import into mitochondria in Saccharomyces cerevisiae but is essential for assembly of the complex. 921 95

Phylogenetic relationships among Tibetan populations of the Bufo bufo species group are investigated using 1063 bases of mitochondrial DNA sequence from the genes encoding ND1 (subunit one of NADH dehydrogenase), tRNA(Ile), tRNA(Gln), tRNA(Met), and ND2. The aligned sequences contain 181 phylogenetically informative characters across all taxa sampled. Two hypotheses for colonization of the Tibetan Plateau are tested. A vicariant hypothesis predicts monophyly of populations from high elevations. A dispersalist hypothesis predicts monophyly of populations in each of two river drainages (Yangtze and Yellow rivers), which requires nonmonophyly of populations from high elevations. Both hypotheses are rejected in favor of a third hypothesis that combines elements of vicariance and dispersal. The most parsimonious phylogenetic tree places the high-elevation species, B. andrewsi, as the sister taxon to the other Asian Bufo populations; these high-elevation populations are postulated to have had a vicariant origin approximately 5 million years before present. The high-elevation population recognized as B. minshanicus is nested within low-elevation populations of B. gargarizans and is suggested to have dispersed onto the Tibetan Plateau more recently.
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PMID:Phylogenetic relationships of toads in the Bufo bufo species group from the eastern escarpment of the Tibetan Plateau: a case of vicariance and dispersal. 947 97

The complete nucleotide sequence of the Chlamydomonas eugametos (Chlamydomonadales, Chlorophyceae, sensu Mattox and Stewart) mitochondrial genome has been determined (22,897 bp, 34.6% G + C). The genes identified in this circular-mapping genome include those for apocytochrome b, subunit 1 of the cytochrome oxidase complex, subunits 1, 2, 4, 5, and 6 of the NADH dehydrogenase complex, discontinuous large and small subunit ribosomal rRNAs and three tRNAs whose anticodons CAU, CCA and UUG are specific for methionine, tryptophan and glutamine, respectively. The C. eugametos mitochondrial DNA (mtDNA), therefore, shares almost the same reduced set of coding functions and similar unusual features of rRNA gene organization with the linear 15.8 kb mtDNA of Chlamydomonas reinhardtii, the only other completely sequenced chlamydomonadalean mtDNA. However, sequence analysis of the C. eugametos mtDNA has revealed the following distinguishing features relative to those of C. reinhardtii: (1) the absence of a reverse transcriptase-like gene homologue, (2) the presence of an additional gene for tRNA(met) that may be a pseudogene, (3) a completely different gene order, (4) transcription of all genes from the same mtDNA strand, (5) a lower G + C content, (6) less pronounced bias in codon usage, and (7) nine group I introns, several of which contain open reading frames coding for potential maturases/endonucleases and two have a nucleotide at the 5' or 3' splice site of the deduced precursor RNAs that deviates from highly conserved nucleotides reported in other group I introns. The features of mitochondrial genome organization and gene content shared by C. eugametos and C. reinhardtii contrast with those of other green algal mtDNAs that have been characterized in detail. The deep evolutionary divergence between these two Chlamydomonas taxa within the Chlamydomonadales suggests that their shared features of mitochondrial genome organization evolved prior to the origin of this group.
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PMID:Complete sequence of the mitochondrial DNA of Chlamydomonas eugametos. 948 40

The nucleotide sequences of two segments of 6,737 ntp and 258 nto of the 18.4-kb circular mitochondrial (mt) DNA molecule of the soft coral Sarcophyton glaucum (phylum Cnidaria, class Anthozoa, subclass Octocorallia, order Alcyonacea) have been determined. The larger segment contains the 3' 191 ntp of the gene for subunit 1 of the respiratory chain NADH dehydrogenase (ND1), complete genes for cytochrome b (Cyt b), ND6, ND3, ND4L, and a bacterial MutS homologue (MSH), and the 5' terminal 1,124 ntp of the gene for the large subunit rRNA (1-rRNA). These genes are arranged in the order given and all are transcribed from the same strand of the molecule. The smaller segment contains the 3' terminal 134 ntp of the ND4 gene and a complete tRNA(f-Met) gene, and these genes are transcribed in opposite directions. As in the hexacorallian anthozoan, Metridium senile, the mt-genetic code of S. glaucum is near standard: that is, in contrast to the situation in mt-genetic codes of other invertebrate phyla, AGA and AGG specify arginine, and ATA specifies isoleucine. However, as appears to be universal for metazoan mt-genetic codes, TGA specifies tryptophan rather than termination. Also, as in M. senile the mt-tRNA(f-Met) gene has primary and secondary structural features resembling those of Escherichia coli initiator tRNA, including standard dihydrouridine and T psi C loop sequences, and a mismatched nucleotide pair at the top of the amino-acyl stem. The presence of a mutS gene homologue, which has not been reported to occur in any other known mtDNA, suggests that there is mismatch repair activity in S. glaucum mitochondria. In support of this, phylogenetic analysis of MutS family protein sequences indicates that the S. glaucum mtMSH protein is more closely related to the nuclear DNA-encoded mitochondrial mismatch repair protein (MSH1) of the yeast Saccharomyces cerevisiae than to eukaryotic homologues involved in nuclear function, or to bacterial homologues. Regarding the possible origin of the S. glaucum mtMSH gene, the phylogenetic analysis results, together with comparative base composition considerations, and the absence of an MSH gene in any other known mtDNA best support the hypothesis that S. glaucum mtDNA acquired the mtMSH gene from nuclear DNA early in the evolution of octocorals. The presence of mismatch repair activity in S. glaucum mitochondria might be expected to influence the rate of evolution of this organism's mtDNA.
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PMID:Mitochondrial DNA of the coral Sarcophyton glaucum contains a gene for a homologue of bacterial MutS: a possible case of gene transfer from the nucleus to the mitochondrion. 954 36


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