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Query: UNIPROT:P06889 (Mol)
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Comamonas testosteroni strain R5 is a phenol-degrading bacterium which expresses a phenol-oxygenating activity that is characterized by low Ks (the apparent half-saturation constant in Haldane's equation) and low K(SI) (the apparent inhibition constant) values. We have now cloned the gene cluster encoding a phenol hydroxylase (phcKLMNOP) and its cognate regulator (phcR) from strain R5. Transformation of Pseudomonas aeruginosa PAO1c (Phenol Catechol+) with pROR502, a derivative of pRO1614 containing the cloned genes, confers the ability to grow on phenol as the sole carbon source. The Ks and K(SI) values for the phenol-oxygenating activity of PAO1c(pROR502) are almost identical to those of strain R5, suggesting that the phcKLMNOP genes encode the major phenol hydroxylase in strain R5. A phylogenetic analysis shows the phenol hydroxylase from strain R5 to be more closely related to toluene/benzene-2-monooxygenase (Tb2m) from Pseudomonas sp. JS150 than to the phenol hydroxylases from P. putida CF600 and BH, or to the phenol hydroxylase from Ralstonia eutropha E2. Analysis of the substrate specificity of PAO1c(pROR502) and PAO1c derivatives expressing phenol hydroxylase from P. putida BH or from R. eutropha E2 indicates that these phenol hydroxylases catalyze the oxidation not only of phenol and cresols but also of toluene and benzene.
Mol Gen Genet 1999 Oct
PMID:Characterization of a high-affinity phenol hydroxylase from Comamonas testosteroni R5 by gene cloning, and expression in Pseudomonas aeruginosa PAO1c. 1058 44

EPR linewidth measurements of PD-Tempone in toluene at 1 (L-Band), 4 (S-Band), 9 (X-Band) and 34 GHz (Q-Band) microwave frequencies indicate the presence of a distribution of relaxation times. The empirical response parameter introduced by Cole-Davidson for the analysis of dielectric relaxation in liquids has been used for the analysis of EPR relaxation data in the low frequency region. The Cole-Davidson parameter can assume values in the range 0 < beta < or = 1. When beta = 1, one obtains the Debye-type spectral density. The calculated linewidth data at 1 GHz agrees with a Cole-Davidson distribution function with a width parameter 0.83 +/- 0.04 for a spherical solute. Beta < 1 at L-band suggests the presence of an asymmetrical distribution of relaxation times associated with different modes of relaxation mechanisms or internal molecular motions. This study shows EPR experiments at low microwave frequencies are more sensitive to the shape of the correlation function.
Spectrochim Acta A Mol Biomol Spectrosc 2000 Feb 01
PMID:Frequency dependent study of the correlation functions in EPR spectroscopy--the Cole-Davidson approach 1. Perdeuterated 2,2,6,6-tetramethyl-4-piperidone N-oxide in toluene. 1072 45

The photochemical reactions of bis(diethyl-diselenocarbamato)copper(II), Cu(Et2dsc)2, complex have been studied in toluene, CH2Cl2, CHCl3 and chloroalkane/EtOH mixed solvents. Charge-transfer irradiation induces intramolecular oxidation of the ligand and reduction of copper(II) to copper(I) as evidenced by EPR and UV-Vis spectra of the complex as well as quantum yield results. When photolysis is carried out in CHCl3 or CH2Cl2 or in the solvent mixture CHCl3/EtOH resp. CH2Cl2/EtOH of lower than 1:1 EtOH content, the primary photoproduct CuI(Et2dsc) is further oxidised in a dark reaction with the chloroalkane producing the corresponding paramagnetic mixed-ligand CuII(Et2dsc)Cl complex in equilibrium with its chloride-bridged and EPR silent, dimeric form Cu2(Et2dsc)2Cl2. At low concentration of EtOH the equilibrium is shifted to the dimeric form whereas at higher than 1:1 EtOH content in the mixed solvent CHCl3/EtOH it is shifted to CuII(Et2dsc)Cl. A reaction mechanism is proposed and the role of ethanol is discussed.
Spectrochim Acta A Mol Biomol Spectrosc 2000 Feb 01
PMID:Charge-transfer photochemistry of bis(diethyl-diselenocarbamato)copper(II). 1072 52

Age- and sex-related changes in toluene metabolism by hepatic microsomes of male and female Sprague-Dawley (SD) rats (1 to 20 weeks) were investigated. A major metabolite of toluene, benzyl alcohol (BA), was measured by high-performance liquid chromatography (HPLC). At low substrate toluene concentrations (0.4 mM), in male rats, BA increased dramatically with development, reaching a peak at 5 weeks of age, rapidly decreasing thereafter. In female rats, BA increased dramatically with development at 3 to 5 weeks of age, and then declined gradually to a low level. Gender differences were obtained at 5 and 20 weeks of age, with BA products being higher in males than in females. At high substrate toluene concentrations (5.0 mM), in male rats, the BA formation pattern was similar to that at the low substrate concentration, although the rate of increase with age was slower. In female rats, a peak was obtained at 3 weeks of age, and then declined gradually to a low level. Gender differences were obtained at 5, 15 and 20 weeks of age, with BA products being higher in males than in females. These results indicate that toluene metabolism exhibits age and gender differences.
Res Commun Mol Pathol Pharmacol 1999
PMID:Age- and sex-related changes in toluene metabolism by rat hepatic microsomes in vitro. 1074 77

Inhalable solvents possess significant abuse liability and produce many of the neurobehavioral effects typically associated with central nervous system-depressant agents, including motor incoordination, anxiolysis, and the elicitation of signs of physical dependence on withdrawal. We tested the hypothesis that the commonly abused solvents toluene, 1,1,1-trichloroethane (TCE), and trichloroethylene (TCY) affect ligand-gated ion channel activity, as do other classes of central nervous system-depressive agents. TCE and toluene, like ethanol, reversibly enhanced gamma-aminobutyric acid (GABA)(A) receptor-mediated synaptic currents in rat hippocampal slices. All three inhalants significantly and reversibly enhanced neurotransmitter-activated currents at alpha1beta1 GABA(A) and alpha1 glycine receptors expressed in Xenopus oocytes. We previously identified specific amino acids of glycine and GABA(A) receptor subunits mediating alcohol and volatile anesthetic enhancement of receptor function. Toluene, TCE, and TCY were tested on several glycine receptor mutants, some of which were insensitive to ethanol and/or enflurane. Toluene and TCY enhancement of glycine receptor function was seen in all these mutants. However, the potentiating effects of TCE were abolished in three mutants and enhanced in two, a pattern more akin to that seen with enflurane than ethanol. These data suggest that inhaled drugs of abuse affect ligand-gated ion channels, and that the molecular sites of action of these compounds may overlap with those of ethanol and the volatile anesthetics.
Mol Pharmacol 2000 Jun
PMID:Glycine and gamma-aminobutyric acid(A) receptor function is enhanced by inhaled drugs of abuse. 1082 91

Sphingomonas yanoikuyae strain B1 is able to degrade a wider range of aromatic hydrocarbons than S. paucimobilis strain TNE12 can degrade. Various culture techniques were used to corroborate that B1 used m-xylene, biphenyl, toluene, naphthalene, and phenanthrene as sole carbon and energy sources. In contrast, TNE12 could not mineralize m-xylene, biphenyl, toluene, or naphthalene. However, fluoranthene served as carbon and energy source for TNE12 but not B1. Southern blots were performed using the cloned genomic region (approximately 23 kb) containing the degradative genes for the upstream pathways for biphenyl and m-xylene and a TOL plasmid-type meta operon from B1 as a probe against the KpnI restriction-digested total DNA of TNE12. This 23 kb probe hybridized to three KpnI-digested fragments of TNE12 DNA; thus significant homology existed between the aromatic hydrocarbon-degrading genes of B1 and TNE12. Further work with smaller probes revealed, however, that TNE12 DNA fragments did not hybridize with the probe containing the genes encoding for xylene monooxygenase and part of an aromatic dioxygenase. A recombinant plasmid, which contains only the genes for xylene monooxygenase, is able to complement TNE12 on m-xylene. These genes are, therefore, probably missing from TNE12. Hence, TNE12 cannot use monocyclic aromatics whereas B1 can. Pulsed field gel electrophoresis coupled with Southern blotting revealed that the aromatic degradative genes were on an approximately 240 kb plasmid of TNE12; the same genes in B1 are known to be chromosomal.
Mol Cells 2000 Apr 30
PMID:Physiological and genetic comparison of two aromatic hydrocarbon-degrading Sphingomonas strains. 1085 Jun 62

Denitrifying strain EbN1 utilizes either ethylbenzene or toluene as the sole source of organic carbon under strictly anoxic conditions. When cells were grown on ethylbenzene, 1-phenylethanol and acetophenone were detected in the culture supernatant. However, these two compounds were not observed when cells were grown on benzoate. Growth on ethylbenzene, 1-phenylethanol, or acetophenone strictly depended on the presence of CO2, whereas growth on benzoate did not. These results suggest that strain EbN1 degrades ethylbenzene via 1-phenylethanol and acetophenone as intermediates, and that acetophenone is subsequently carboxylated. In suspensions of benzoate-grown cells, induction was required for degradation of ethylbenzene, 1-phenylethanol, and acetophenone. Induction was also required for toluene-grown cells to gain activity to degrade ethylbenzene, and, conversely, for ethylbenzene-grown cells to degrade toluene. In accordance with our findings from these studies, two-dimensional gel electrophoretic analysis of extracts of cells grown on benzoate, acetophenone, ethylbenzene, or toluene showed that a number of substrate-specific proteins were induced in strain EbN1. Growth on toluene or ethylbenzene induced a distinct set of proteins. However, some of the induced proteins in ethylbenzene or acetophenone grown cells were identical. This agrees with the finding that acetophenone is an intermediate in the degradation of ethylbenzene.
J Mol Microbiol Biotechnol 1999 Aug
PMID:Anaerobic degradation of ethylbenzene and toluene in denitrifying strain EbN1 proceeds via independent substrate-induced pathways. 1094 98

In the presence of toluene and other structural analogues, the enhancer binding protein XylR activates the sigma54 promoter Pu of the TOL (toluene degradation) plasmid pWW0 of Pseudomonas putida. Introduction of amino acid changes Val-219Asp and Ala-220Pro, which enter a proline kink at the interdomain region (B linker) between the A (signal reception) module and the central portion of XylR, originated a protein with unforeseen properties. These included a minor ability to activate Pu in the absence of aromatic effectors, a much higher responsiveness to m-xylene and a significant response to a large collection of aromatic inducers. Such changes could not be attributed to variations in XylR expression levels or to the fortuitous creation of a novel promoter, but to a genuine change in the properties of the activator. Structural predictions suggested that the mutation entirely disrupted an otherwise probable coiled-coil structure. A second directed mutant within the same region consisting of a major replacement of amino acids A220-N221 by the peptide HHHR produced an even more exacerbated phenotype. These data support a model in which the linker B region influences the effector profile by modifying at a distance the operative shape of the effector pocket and fixing the protein in an intermediate step of the activation process.
Mol Microbiol 2000 Oct
PMID:The role of the interdomain B linker in the activation of the XylR protein of Pseudomonas putida. 1106 65

We determined whether prior treatment of rats (study 1) with subthreshold doses of iron (no evidence of cardiac tissue overload), or in vitro ischemic pre-conditioning (IP: 5 min. Ischemia (I)/5 min. Reperfusion (R) x 2 cycles) of hearts from untreated rats (study 2), can modulate redox-active cardiac tissue iron levels or distribution, leading to alterations in post-ischemic lipid peroxidation-derived free radical (FR) production and severity of reperfusion injury. In study 1, rats received biweekly i.p. injections of 0 (saline=S), 3, 6, or 12 mg FeCl3/ml for 3-wks prior to imposing 30 min. I/15 min. R in vitro. The highest dose caused no elevations in plasma or heart tissue Fe levels, but did further reduce post-ischemic recoveries of left ventricular developed pressure (17% lower), cardiac work (57%) and output (54%), and increased effluent lipid hydroperoxides (2.1-fold) compared to the S-group. Post-ischemic FR production was assessed in toluene-extracted effluent by ESR spectroscopy and alpha-phenyl-N-tert butylnitrone (PBN=2.5 mM perfusate) spin trapping. PBN/alkoxyl (alphaH=1.90 G, alphaN=13.63 G) was the dominant signal detected in all groups; however, Fe-treated groups displayed significant dose-dependent increases in total alkoxyl content (3, 6, 12 mg/ml: 1.8-, 2.3-, 2.7-fold higher) compared to the S-group. These data suggest that even mild, non-overloading doses of iron can be functionally and oxidatively detrimental to hearts when an I/R stress is imposed. In study 2, isolated hearts from untreated rats were exposed to two-IP cycles: during IP, total effluent iron content (atomic absorption) increased 11.4-fold compared to control and analysis of cardiovascular tissue iron distribution (X-ray microanalysis) suggested that iron loss from capillary endothelium was far greater than from tissue myocytes. Moreover, iron-catalyzed production of alkoxyl radicals following severe I/R stress (40 min. I/15 min. R) was substantially lower (73%) in IP hearts compared to the non-IP counterparts. These preliminary findings suggest that cardioprotection resulting from IP may, in part, be related to IP-induced release of cardiovascular endothelial iron (redox-active) prior to imposing severe I/R stress.
Cell Mol Biol (Noisy-le-grand) 2000 Dec
PMID:Cardiac tissue iron: effects on post-ischemic function and free radical production, and its possible role during preconditioning. 1115 77

[70]Fullerene has been shown to form 1:1 molecular complexes with toluene, p-xylene, m-xylene, 1,2,4,5-tetramethyl benzene (durene) and pentamethyl benzene (PMB) in CCl4 medium by absorption spectroscopic method. Isosbestic points have been detected in case of complexes with PMB and durene. Charge transfer absorption band could not be detected but the intensity of the broad absorption band of C70 in CCl4 decreases systematically with increase in the concentration of the added methylbenzenes. From this trend the formation constants (Kc) of the complexes have been determined at three different wavelengths. The constancy of Kc with respect to change in the wavelength of measurement supports the view that complex of a single stoichiometry (1:1) is formed in each case.
Spectrochim Acta A Mol Biomol Spectrosc 2001 Feb
PMID:Absorption spectroscopic study of EDA complexes of. 1120 65


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