Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “NAPHTHALENE”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 901 records · Page 50Linked to original sources
PubMed1995

The 4-hydroxy-2-oxovalerate aldolase and acetaldehyde dehydrogenase (acylating) encoded by the nahM and nahO genes of the naphthalene catabolic plasmid pWW60-22 provide further evidence of conservation of meta-cleavage pathway gene sequences.

We report the complete nucleotide sequence and over-expression of the nahOM genes for the acetaldehyde dehydrogenase (acylating) and the 4-hydroxy-2-oxovalerate aldolase from the meta pathway operon of the naphthalene catabolic plasmid pWW60-22 from Pseudomonas sp. NCIMB9816. Additional partial sequence analysis of adjacent DNA shows the gene order within the operon to be nahNLOMK, identical to the order found for the isofunctional genes in the meta pathway operons in the toluene/xylene pathway of TOL plasmid pWW0 and the phenol/methylphenol pathway of pVI150. The deduced amino acid sequences of NahO and NahM were significantly homologous to the equivalent enzymes encoded by other Pseudomonas meta pathways, although both were the most divergent in each comparison. The nahOM genes were inserted downstream of the T7 promoter in the expression vector pET3a and similar constructs were also made of the isofunctional regions from pVI150 (dmpFG) and TOL plasmid pDK1 (xyIQK). High expression of all three gene pairs was detected by enzyme assays and by SDS-PAGE.

Aldehyde Oxidoreductases↗
PubMed2005

(Di-2-pyridylamine-kappa2N,N')(naphthalene-2,3-diolato-kappa2O,O')palladium(II) monohydrate and (di-2-pyridylamine-kappa2N,N')(3-oxidonaphthalene-2-carboxylato-kappa2O,O')palladium(II).

In the title complexes, [Pd(C10H6O2)(C10H9N3)].H2O, (I), and [Pd(C11H6O3)(C10H9N3)], (II), the Pd(II) centers have a distorted cis-square-planar geometry. In (I), the Pd(II) atom is coordinated to two N atoms of the di-2-pyridylamine (DPA) ligand and two O atoms of the naphthalene-2,3-diolate (ND) dianion. In (II), the Pd(II) atom is coordinated to two N atoms of the DPA ligand, one carboxylate O atom and one oxide O atom from the 3-oxidonaphthalene-2-carboxylate (NC) ligand. The dihedral angle between the planes of the two pyridine rings of DPA in (I) is 16.20 (12) degrees and that in (II) is 29.45 (10) degrees . In (I), the molecules are linked by N-H...O and O-H...O hydrogen bonds to generate centrosymmetric dimers. In (II), molecules are linked by N-H...O and C-H...O hydrogen bonds to generate spirals.

Amines↗
PubMed1998

1-(o-tolylmethyl)naphthalene-2-carboxylic acid.

The title acid, C19H16O2, crystallized in space group P1. In this structure, a hydrogen bond of the 'cyclic dimer' type is formed about a center of symmetry. The O(donor)...O(acceptor) distance is 2.647 (1) A. The carboxylic H and O atoms are ordered. The dihedral angle between the best-fit naphthalene plane and the carboxylic acid group plane is 11.1 (2) degrees.

Carboxylic Acids↗
PubMed1993

Dramatic improvements in viral inactivation with brominated psoralens, naphthalenes and anthracenes.

Amino or polyamino derivatives of naphthalene (N-H), anthracene (A-H) and 8-alkoxypsoralen (PSR-H) were prepared along with their monobrominated analogs (N-Br, A-Br and PSR-Br). The ammonium salts of these compounds are all water soluble and bind strongly to calf thymus DNA and to lambda phage, a double-helical DNA, protein-coated virus. Binding of the sensitizer to DNA occurs, presumably by a mixture of hydrophobic, intercalative and electrostatic interactions. Relative binding constants to calf thymus DNA and to lambda phage were measured by the ethidium bromide fluorescence quenching assay. In general the brominated analogs bind more tightly to calf thymus DNA and to the virus than to the nonhalogenated analogs. It is demonstrated that the brominated aromatics are much more effective at inactivating lambda phage upon photoactivation (lambda approximately 310 or 350 nm) than are their nonbrominated analogs. At identical sensitizer concentrations (by weight) and light flux N-Br, A-Br, and PSR-Br produce 5-6 more logs of viral inactivation than their nonbrominated counterparts (N-H, A-H and PSR-H, respectively). The bromine effect may originate from light-induced electron transfer and subsequent cleavage of the C-Br bond of the sensitizer radical anion bonds to form aryl radicals. Singlet oxygen cannot be responsible for the viral inactivation because the brominated sensitizers are equally effective in the presence and absence of oxygen. Dithiothreitol does not protect lambda phage from light-induced inactivation by the brominated sensitizer thereby demonstrating that the photogenerated reactive intermediates responsible for the effect are complexed to the virus and are not generated free in solution.

Animals↗
PubMed1983

Expression of naphthalene oxidation genes in Escherichia coli results in the biosynthesis of indigo.

A fragment of plasmid NAH7 from Pseudomonas putida PpG7 has been cloned and expressed in Escherichia coli HB101. Growth of the recombinant Escherichia coli in nutrient medium results in the formation of indigo. The production of this dye is increased in the presence of tryptophan or indole. Several bacteria that oxidize aromatic hydrocarbons to cis-dihydrodiols also oxidize indole to indigo. The results suggest that indigo formation is due to the combined activities of tryptophanase and naphthalene dioxygenase.

Cloning, Molecular↗
PubMed1988

New naphthalene-degrading marine Pseudomonas strains.

Over 100 strains that utilized naphthalene as the only carbon and energy source were isolated from samples of marine sediments taken from a heavily polluted area. The isolates were characterized taxonomically and physiologically. Most of these strains belonged to the genus Pseudomonas, and seven of them did not fit any previous taxonomic description. They differed from type strains in a few biochemical characteristics and in the utilization of aromatic compounds. None had catechol 1,2-dioxygenase activity, and catechol 2,3-dioxygenase was responsible for the aromatic ring cleavage. DNA hybridization demonstrated a close relationship between two isolates and the Pseudomonas stutzeri type strain, and between five isolates and the Pseudomonas testosteroni type strain. On the basis of nutritional and enzymatic characteristics, it was assumed that the seven isolates represent new biovars belonging to the species P. testosteroni and P. stutzeri that are able to degrade aromatic hydrocarbons.

Biodegradation, Environmental↗
PubMed1995

Competitive metabolism of naphthalene, methylnaphthalenes, and fluorene by phenanthrene-degrading pseudomonads.

Polynuclear aromatic hydrocarbons (PAHs) typically exist as complex mixtures in contaminated soils, yet little is known about the biodegradation of PAHs in mixtures. We have isolated two physiologically diverse bacteria, Pseudomonas stutzeri P-16 and P. saccharophila P-15, from a creosote-contaminated soil by enrichment on phenanthrene as the sole carbon source and studied their ability to metabolize several other two- and three-ring PAHs. Naphthalene, 1-methylnaphthalene, and 2-methylnaphthalene served as growth substrates for both organisms, while fluorene was only cometabolized. We also studied the effects of these compounds on initial rates of phenanthrene uptake in binary mixtures. Lineweaver-Burk analysis of kinetic measurements was used to demonstrate competitive inhibition of phenanthrene uptake by all four compounds, suggesting that multiple PAHs are being transformed by a common enzyme pathway in whole cells. Estimates of the inhibition coefficient, Ki, are reported for each compound. The occurrence of competitive metabolic processes in physiologically diverse organisms suggests that competitive metabolism may be a common phenomenon among PAH-degrading organisms.

Binding, Competitive↗
PubMed1997

Carboxylation as an initial reaction in the anaerobic metabolism of naphthalene and phenanthrene by sulfidogenic consortia.

The anaerobic biodegradation of naphthalene (NAP) and phenanthrene (PHE) was investigated by using sediment collected from the Arthur Kill in New York/New Jersey harbor. The initial cultures were composed of 10% sediment and 90% mineral medium containing 20 mM sulfate. Complete loss of NAP and PHE (150 to 200 muM) was observed after 150 days of incubation. Upon refeeding, NAP and PHE were utilized within 14 days. The utilization of both compounds was inhibited in the presence of 20 mM molybdate. [14C]NAP and [14C]PHE were mineralized to 14CO2. The activities could be maintained and propagated by subculturing in mineral medium. In the presence of halogenated analogs, 2-naphthoate was detected in NAP-utilizing enrichments. The mass spectrum of the derivatized 2-napththoate from the enrichment supplemented with both [13C]bicarbonate and NAP indicates the incorporation of 13CO2 into NAP. In the PHE-utilizing enrichment, a metabolite was detected by both high-pressure liquid chromatography and gas chromatography-mass spectrometry analyses. The molecular ion and fragmentation pattern of its mass spectrum indicate that it was phenanthrenecarboxylic acid. The results obtained with [13C] bicarbonate indicate that 13CO2 was incorporated into PHE. It appears, therefore, that carboxylation is an initial key reaction for the anaerobic metabolism and NAP and PHE. To our knowledge, this is the first report providing evidence for intermediates of PAH degradation under anaerobic conditions.

Anaerobiosis↗
PubMed1997

Biodegradation of petroleum hydrocarbons by psychrotrophic Pseudomonas strains possessing both alkane (alk) and naphthalene (nah) catabolic pathways.

Three hydrocarbon-degrading psychrotrophic bacteria were isolated from petroleum-contaminated Arctic soils and characterized. Two of the strains, identified as Pseudomonas spp., degraded C5 to C12 n-alkanes, toluene, and naphthalene at both 5 and 25 degrees C and possessed both the alk catabolic pathway for alkane biodegradation and the nah catabolic pathway for polynuclear aromatic hydrocarbon biodegradation. One of these strains contained both a plasmid slightly smaller than the P. oleovorans OCT plasmid, which hybridized to an alkB gene probe, and a NAH plasmid similar to NAH7, demonstrating that both catabolic pathways, located on separate plasmids, can naturally coexist in the same bacterium.

Alkanes↗
PubMed1974

Purification and propeties of (plus)-cis-naphthalene dihydrodiol dehydrogenase of Pseudomonas putida.

Cells of Pseudomonas putida, after growth with naphthalene as sole source of carbon and energy, contain an enzyme that oxidizes (+)-cis-1(r),2(s)-dihydroxy-1,2-dihydronaphthalene to 1,2-dihydroxynaphthalene. The purified enzyme has a molecular weight of 102,000 and apparently consists of four 25,500 molecular weight subunits. The enzyme is specific for nicotinamide adenine dinucleotide as an electron acceptor and also oxidizes several other cis-dihydrodiols. However, no enzymatic activity was observed with trans-1,2-dihydronaphthalene, or the K-region cis-dihydrodiols of carcinogenic polycyclic hydrocarbons.

Cell-Free System↗
PubMed1980

Naphthalene metabolism by pseudomonads: purification and properties of 1,2-dihydroxynaphthalene oxygenase.

1,2-Dihydroxynaphthalene oxygenase was purified from Pseudomonas putida NCIB 9816 grown on naphthalene as the sole source of carbon and energy. The enzyme had a subunit molecular weight of 19,000 and in a medium containing phosphate buffer, 1 mM mercaptoethanol, and 10% (vol/vol) ethanol had a native molecular weight greater than 275,000. The enzyme required Fe2+ for activity. It was inactivated slowly on standing, and inactivation was accelerated by dilution with aerated buffers and by H2O2. Bathophenanthroline sulfonate, o-phenanthroline, 8-hydroxyquinoline, and 2,2'-dipyridyl also inhibited the enzyme. The inactive enzyme was reactivated by anaerobic incubation with ferrous sulfate and ferrous ammonium sulfate. Thiol reagents and acetone, ethanol, or glycerol decreased the rate of loss of activity. The enzyme was most active with 1,2-dihydroxynaphthalene, for which the Km was 2.8 X 10(-4) M. 3-Methyl- and 4-methylcatechols were oxidized at 3 and 1.5%, respectively, of the rate of 1,2-dihydroxynaphthalene, and the Km for 3-methylcatechol was 1.5 X 10(-4) M. Purified 1,2-dihydroxynaphthalene oxygenase catalyzed the oxidation of 1,2-dihydroxynaphthalene, leading to the appearance of 2-hydroxychromene-2-carboxylic acid, but 3-methylcatechol was oxidized by this enzyme to 2-hydroxy-6-oxoheptadienoic acid. Thus, a product structurally analogous to 2-hydroxychromene-2-carboxylic acid was not observed when 3-methylcatechol was oxidized. This may indicate that 2-hydroxychromene-2-carboxylic acid results from cyclization of a ring fission product before release from the enzyme.

Dioxygenases↗
PubMed1985

Regulation of naphthalene catabolic genes of plasmid NAH7.

Tn5 insertion mutations defining a regulatory gene, nahR, of the naphthalene catabolic pathway encoded by the NAH7 plasmid were mapped within a small NAH7 region only a few hundred bases upstream of the nahG gene, the most promoter-proximal gene of the nahGHIJK operon. The nahR mutations blocked the induction of both the nahABCDEF and nahGHIJK operons, and the defect was completely corrected in the presence of the wild-type allele in a trans position. The pleiotropic, recessive, and negative nature of these mutations indicates that the nahR gene specifies a regulatory element which is required to activate both nah operons.

Chromosome Mapping↗
PubMed1994

Organization and evolution of naphthalene catabolic pathways: sequence of the DNA encoding 2-hydroxychromene-2-carboxylate isomerase and trans-o-hydroxybenzylidenepyruvate hydratase-aldolase from the NAH7 plasmid.

The sequence of a 2,437-bp DNA segment from the naphthalene upper catabolic pathway operon of plasmid NAH7 was determined. This segment contains three large open reading frames designated nahQ', nahE, and nahD. The first of these is the 3' end of an open reading frame that has no known function, the second (993 bp) encodes trans-o-hydroxybenzylidenepyruvate hydratase-aldolase (deduced molecular weight, 36,640), and the third (609 bp) encodes 2-hydroxychromene-2-carboxylate isomerase (deduced molecular weight, 23,031). This DNA has a high degree of sequence homology (greater than 91% for the first 2161 bp) with a DNA segment from the dox (dibenzothiophene oxidation) operon of Pseudomonas sp. strain C18, which encodes a pathway analogous to that encoded by NAH7. However, 84 bp downstream from nahD, the last gene in the nah operon, this homology ends. This 84-bp sequence at the downstream end of nah and dox homology has 76% homology to a sequence that occurs just upstream of the nah promoter in NAH7. These directly repeated 84-bp sequences thus encompass the upper-pathway nah operon and constitute the ends of a highly conserved region.

Amino Acid Sequence↗
PubMed2000

Characterization of three XylT-like [2Fe-2S] ferredoxins associated with catabolism of cresols or naphthalene: evidence for their involvement in catechol dioxygenase reactivation.

The xylT gene product, a component of the xylene catabolic pathway of Pseudomonas putida mt2, has been recently characterized as a novel [2Fe-2S] ferredoxin which specifically reactivates oxygen-inactivated catechol 2,3-dioxygenase (XylE). In this study, three XylT-like proteins potentially involved in the catabolism of naphthalene (NahT) or cresols (PhhQ and DmpQ) have been overexpressed in Escherichia coli, purified, and compared with respect to their biochemical properties and interaction with XylE. The three XylT analogues show general spectroscopic characteristics common to plant-type [2Fe-2S] ferredoxins as well as distinctive features that appear to be typical for the XylT subgroup of these proteins. The midpoint redox potentials of the PhhQ and DmpQ proteins were -286 mV and -323 mV, respectively. Interestingly, all purified XylT-like proteins promoted in vitro reactivation of XylE almost as efficiently as XylT. The interaction of XylE with XylT and its analogues was studied by cross-linking experiments using the 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide. A polypeptide band with an M(r) of 46,000, which corresponded to the cross-linked product between one XylE subunit and one molecule of ferredoxin, was obtained in all cases. The formation of the complex was affected by ionic strength, indicating that electrostatic forces are involved in the dioxygenase-ferredoxin interaction. In complementation experiments, plasmids expressing xylT or its analogues were introduced into an XylT-null mutant of P. putida which is unable to grow on p-methylbenzoate. All transconjugants regained the wild-type phenotype, indicating that all analogues can substitute for XylT in the in vivo reactivation of XylE. Our results provide evidence for a subgroup of [2Fe-2S] ferredoxins with distinct biochemical properties whose specific function is to reactivate intrinsically labile extradiol ring cleavage dioxygenases involved in the catabolism of various aromatic hydrocarbons.

Amino Acid Sequence↗
PubMed2000

Evidence for plasmid-mediated chemotaxis of Pseudomonas putida towards naphthalene and salicylate.

A naphthalene (Nap) and salicylate (Sal) degrading microorganism, Pseudomonas putida RKJ1, is chemotactic towards these compounds. This strain carries a 83 kb plasmid. A 25 kb EcoRI fragment of the plasmid contains the genes responsible for Nap degradation through Sal. RKJ5, the plasmid-cured derivative of RKJ1, is neither capable of degradation nor is chemotactic towards Nap or Sal. The recombinant plasmid pRKJ3, which contained a 25 kb EcoRI fragment, was transferred back into the plasmid-free wild-type strain RKJ5, and the transconjugant showed both degradation and chemotaxis. The recombinant plasmid pRKJ3 was also transferred into motile, plasmid-free P. putida KT2442. The resulting transconjugant (RKJ15) showed chemotaxis towards both Nap and Sal. Two mutant strains carrying deletions in pRKJ3 (in KT2442) with phenotypes Nap- Sal+ and Nap- Sal-, were also tested for chemotaxis. It was found that the Nap- Sal+ mutant strain showed chemotaxis towards Sal only, whereas the Nap- Sal- mutant strain is non-chemotactic towards both the compounds. These results suggest that the metabolism of Nap and Sal may be required for the chemotactic activity.

Chemotaxis↗
PubMed2005

Confined crystallization in phase-separated poly(ethylene terephthalate)/poly(ethylene naphthalene 2,6-dicarboxilate) blends.

The isothermal cold crystallization of poly(ethylene terephthalate)(PET) in cryogenic mechanical alloyed blends of PET and Poly(ethylene naphthalene 2,6-dicarboxilate)(PEN) 1:1 by weight has been investigated by simultaneous small and wide angle X-ray scattering (SAXS and WAXS) and dielectric spectroscopy (DS). For transesterification levels higher than 23% the blends tend to transform into a one-phase system and the crystallization of PET is strongly inhibited due to the significant reduction of the PET segment length. For lower levels of transesterification the blends are phase separated and the overall crystallization behaviour can be explained considering the confined nature of the PET domains in these blends. The formation of a rigid amorphous phase in the intra-lamellar stack amorphous regions is reduced in the blends due to a lower probability of stack formation in the confined PET-rich domains. The more effective filling of the space by the lamellar crystals in the blends provokes a stronger restriction to the amorphous phase mobility of PET in the blends than in pure PET.

Biocompatible Materials↗
PubMed1992

Enzymatic distribution patterns of rat lenses and the changes that occur during naphthalene cataract development.

The topographic distribution of enzyme activities in normal rat lenses and their changes occurring during naphthalene cataract development were investigated. Cataract formation was documented by slit images according to the Scheimpflug principle. Before the onset of visible changes and after the development of early visible opacities, the animals were sacrificed, their lenses removed and biochemically analyzed. The lenses were divided reproducibly into 6 parts--the equatorial ring and 5 layers of central cylinders from the anterior to the posterior cortex. The enzyme activity spectra (AR, SDH, GR, GPX, PFK, ALD, GAP-DH, and LDH) showed region-related patterns, which could not be detected with analysis of the total lens. Image analysis of the first signs of opacity showed that changes in the activities of several enzymes correlate with density changes in the corresponding lens layers.

Animals↗