Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.23.17 (PCE)
 1,301 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Male albino rats of the Donryu strain were divided into 4 groups: the normal control group, tetrachloromethane (CCl4, TCM) group, tetrachloroethylene (CCl2 = CCl2, PCE) group and trichloroethylene (CHCl = CCl2, TCE) group. Each group was consisted of 6 animals. TCM, PCE and TCE were administered orally at a dosage of 13 mmoles/kg as a 50% v/v olive oil solution to rats 24 hours prior to an oral administration of m-xylene (8.2 mmoles/kg as a 50% v/v olive oil solution). The normal control group was administered only olive oil (2.5 ml/kg) 24 hours prior to m-xylene dose. Urine was collected 24, 48, 72 and 96 hours after administration of m-xylene. The urine was analysed for m-methylhippuric acid (m-MHA) by the paper chromatographic method of Ogata et al. The results obtained were as follows: 1) Total urinary excretion of m-MHA in the normal control group was equivalent on a molar basis to about 58% of m-xylene received, and the major portions of the metabolites were excreted on the 1st day. 2) In TCM group, total urinary excretion of m-MHA was about a half of that in the normal control group. It was equivalent on a molar basis to about 30% of m-xylene received (p less than 0.01), and the urinary excretion of m-MHA on the 1st day was significantly less than those of the normal control group (p less than 0.001) and TCE group (p less than 0.05). 3) In PCE group, urinary excretion of m-MHA on the 1st day was significantly less than that of the normal control group (p less than 0.01) and the excretion was delayed. 4) In TCE group, total urinary excretion of m-MHA was slightly but not significantly less than that of the normal control group (p less than 0.05). 5) In TCM-ip group of rats which were given TCM orally 24 hours prior to the administration of m-xylene by intraperitoneal injection, urinary excretion of m-MHA on the 1st day and in 4 days after administration of m-xylene was less than that of the control-ip group.
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PMID:[Metabolism of m-xylene in rats after administration of chlorinated hydrocarbons (author's transl)]. 61 80

This study describes two methods for the quantitative determination of the residual fumigants ethylene dichloride (EDC), carbon tetrachloride (CCl4), trichloroethylene (TCE), ethylene dibromide (EDB) and tetrachloroethylene (PCE) in cereals (especially wheat) and other foodstuffs. In the first method, a micro steam distillation- solvent extraction apparatus is used, while the second method is based on a headspace technique. For the quantitative determination of carbon tetrachloride in cereals, the multiple headspace technique is not retained because it is too time-consuming. The analysis of the different fumigants is performed by electron-capture gas chromatography, using a fused silica capillary column, CP sil 8 CB. With the steam distillation-solvent extraction method, recoveries from 95.9% to 100.5% are obtained for the fumigants, added at two different levels. The standard deviation varies between 1.1% and 6%. Using the simple headspace technique, recoveries from 73.5% to 85.1% with a standard deviation of between 1.7% and 6.6% have been reached for the fumigants in cereals fortified at two different levels. The absolute detection limits for the five fumigants EDC, CCl4, TCE, EDB and PCE, in both methods, are 30, 0.25, 1.1, and 0.5 pg, respectively.
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PMID:Determination of fumigants in cereals and cereal products by capillary gas chromatography. 322 92

The membrane-bound tetrachloroethene reductive dehalogenase (PCE-RDase) (PceA; EC 1.97.1.8), the terminal component of the respiratory chain of Dehalobacter restrictus, was purified 25-fold to apparent electrophoretic homogeneity. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed a single band with an apparent molecular mass of 60 +/- 1 kDa, whereas the native molecular mass was 71 +/- 8 kDa according to size exclusion chromatography in the presence of the detergent octyl-beta-D-glucopyranoside. The monomeric enzyme contained (per mol of the 60-kDa subunit) 1.0 +/- 0.1 mol of cobalamin, 0.6 +/- 0.02 mol of cobalt, 7.1 +/- 0.6 mol of iron, and 5.8 +/- 0.5 mol of acid-labile sulfur. Purified PceA catalyzed the reductive dechlorination of tetrachloroethene and trichloroethene to cis-1,2-dichloroethene with a specific activity of 250 +/- 12 nkat/mg of protein. In addition, several chloroethanes and tetrachloromethane caused methyl viologen oxidation in the presence of PceA. The K(m) values for tetrachloroethene, trichloroethene, and methyl viologen were 20.4 +/- 3.2, 23.7 +/- 5.2, and 47 +/- 10 micro M, respectively. The PceA exhibited the highest activity at pH 8.1 and was oxygen sensitive, with a half-life of activity of 280 min upon exposure to air. Based on the almost identical N-terminal amino acid sequences of PceA of Dehalobacter restrictus, Desulfitobacterium hafniense strain TCE1 (formerly Desulfitobacterium frappieri strain TCE1), and Desulfitobacterium hafniense strain PCE-S (formerly Desulfitobacterium frappieri strain PCE-S), the pceA genes of the first two organisms were cloned and sequenced. Together with the pceA genes of Desulfitobacterium hafniense strains PCE-S and Y51, the pceA genes of Desulfitobacterium hafniense strain TCE1 and Dehalobacter restrictus form a coherent group of reductive dehalogenases with almost 100% sequence identity. Also, the pceB genes, which may code for a membrane anchor protein of PceA, and the intergenic regions of Dehalobacter restrictus and the three desulfitobacteria had identical sequences. Whereas the cprB (chlorophenol reductive dehalogenase) genes of chlorophenol-dehalorespiring bacteria are always located upstream of cprA, all pceB genes known so far are located downstream of pceA. The possible consequences of this feature for the annotation of putative reductive dehalogenase genes are discussed, as are the sequence around the iron-sulfur cluster binding motifs and the type of iron-sulfur clusters of the reductive dehalogenases of Dehalobacter restrictus and Desulfitobacterium dehalogenans identified by electron paramagnetic resonance spectroscopy.
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PMID:Characterization of the corrinoid iron-sulfur protein tetrachloroethene reductive dehalogenase of Dehalobacter restrictus. 1290 51

The potential for natural attenuation of volatile organic compounds (VOCs) in landfill covers was investigated in soil microcosms incubated with methane and air, simulating the gas composition in landfill soil covers. Soil was sampled at Skellingsted Landfill at a location emitting methane. In total, 26 VOCs were investigated, including chlorinated methanes, ethanes, ethenes, fluorinated hydrocarbons, and aromatic hydrocarbons. The soil showed a high capacity for methane oxidation resulting in very high oxidation rates of between 24 and 112 microg CH4 g(-1) h(-1). All lower chlorinated compounds were shown degradable, and the degradation occurred in parallel with the oxidation of methane. In general, the degradation rates of the chlorinated aliphatics were inversely related to the chlorine to carbon ratios. For example, in batch experiments with chlorinated ethylenes, the highest rates were observed for vinyl chloride (VC) and lowest rates for trichloroethylene (TCE), while tetrachloroethylene (PCE) was not degraded. Maximal oxidation rates for the halogenated aliphatic compounds varied between 0.03 and 1.7 microg g(-1) h(-1). Fully halogenated hydrocarbons (PCE, tetrachloromethane [TeCM], chlorofluorocarbon [CFC]-11, CFC-12, and CFC-113) were not degraded in the presence of methane and oxygen. Aromatic hydrocarbons were rapidly degraded giving high maximal oxidation rates (0.17-1.4 microg g(-1) h(-1)). The capacity for methane oxidation was related to the depth of oxygen penetration. The methane oxidizers were very active in oxidizing methane and the selected trace components down to a depth of 50 cm below the surface. Maximal oxidation activity occurred in a zone between 15 and 20 cm below the surface, as this depth allowed sufficient supply of both methane and oxygen. Mass balance calculations using the maximal oxidation rates obtained demonstrated that landfill soil covers have a significant potential for not only methane oxidation but also cometabolic degradation of selected volatile organics, thereby reducing emissions to the atmosphere.
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PMID:Attenuation of methane and volatile organic compounds in landfill soil covers. 1496 59

The enhanced removal of carbon tetrachloride (CCl4), tetrachloroethene (C2Cl4), and trichloroethene (C2HCl3) by chloride green rust (GR(Cl)) in the presence of copper ions was investigated. X-ray powder diffraction (XRPD) and X-ray photoelectron spectroscopy (XPS) were used to characterize the crystallization and chemical speciation, respectively, of the secondary mineral phases produced in the GR(Cl)-Cu(II) system. The addition of Cu(II) to GR(Cl) suspensions resulted in enhanced dechlorination of the chlorinated hydrocarbons examined in this study. The degradation reactions followed pseudo-first-order kinetics and the pseudo-first-order rate constant (k(obs)) for CCl4 (20 microM) removal by GR(CI) at pH 7.2 was 0.0808 h(-1). Addition of 0.5 mM Cu(II) completely dechlorinated CCl4 within 35 min, and the k(obs) was 84 times greater than that in the absence of Cu(II). Chloroform (CHCl3), the major chlorinated product in CCl4 dechlorination, accumulated at a concentration up to 13 microM in the GR(Cl) system alone, but was completely dechlorinated within 9 h in the GR(Cl)-Cu(II) suspension. Also, rapid removal of C2Cl4 and C2HCl3 by GR(Cl) was observed when Cu(II) was added. The k(obs) values for the removal of chlorinated ethenes were 4.7-7 times higher than that obtained in the absence of Cu(II). In addition, the k(obs) for PCE removal increased linearly with respect to Cu(II) concentrations in the range from 0.1 to 1.0 mM. Addition of Cu(II) at a concentration higher than 1.0 mM decreased the k(obs) for the removal of both C2Cl4 and C2HCl3 due to the decrease in structural Fe(II) concentration in GR(Cl) and the changes in redox potentials and pH values. Moreover, the highest removal efficiency and rate of C2Cl4 was obtained at near-neutral pH when Cu(II) was added into the GR(Cl) suspension. XPS and XRPD results showed that the Fe(II) in the GR(Cl) suspension could reduce Cu(II) to both Cu(I) and metallic Cu. These findings are relevant to the better understanding of the role of abiotic removal of chlorinated hydrocarbons during remediation and/or natural attenuation in iron-reducing environments.
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PMID:Enhanced dechlorination of chlorinated methanes and ethenes by chloride green rust in the presence of copper(II). 1598 86