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At least 19 recordsLinked to original sources
PubMed1979

Epoxide hydrase and glutathione S-transferase activities with selected alkene and adrene oxides in several marine species.

Epoxide hydrase and glutathione (GSH) S-transferase activities were measured in subcellular fractions prepared from liver or hepatopancreas and some extrahepatic organs of a number of marine species common to Maine or Florida. These activities were easily detected in the species studied. In fish, hepatic GSH S-transferase activities were normally higher than hepatic epoxide hydrase activities for the alkene oxide (styrene oxide and octene oxide) and arene oxide (benzo[a]pyrene 4,5-oxide) substrates studied, whereas in crustacea, hepatopancreas epoxide hydrase activities were higher than hepatopancreas GSH S-transferase activities with the same substrates. Extrahepatic organs from fish and crustacea usually had higher GSH S-transferase activities than epoxide hydrase activities with the alkene and arene oxide substrates. GSH S-transferase activity was also found in liver or hepatopancreas of every aquatic species studied and in a number of extrahepatic organs, when 1,2-dichloro-4-nitrobenzene or 1-chloro-2,4-dinitrobenzene served as substrate.

Alkenes↗
PubMed1979

Microbial oxidation of gaseous hydrocarbons: epoxidation of C2 to C4 n-alkenes by methylotrophic bacteria.

Over 20 new cultures of methane-utilizing microbes, including obligate (types I and III) and facultative methylotrophic bacteria were isolated. In addition to their ability to oxidize methane to methanol, resting cell-suspensions of three distinct types of methane-grown bacteria (Methylosinus trichosporium OB3b [type II, obligate]; Methylococcus capsulatus CRL M1 NRRL B-11219 [type I, obligate]; and Methylobacterium organophilum CRL-26 NRRL B-11222 [facultative]) oxidize C2 to C4 n-alkenes to their corresponding 1,2-epoxides. The product 1,2-epoxides are not further metabolized and accumulate extracellularly. Methanol-grown cells do not have either the epoxidation or the hydroxylation activities. Among the substrate gaseous alkenes, propylene is oxidized at the highest rate. Methane inhibits the epoxidation of propylene. The stoichiometry of the consumption of propylene and oxygen and the production of propylene oxide is 1:1:1. The optimal conditions for in vivo epoxidation are described. Results from inhibition studies indicate that the same monooxygenase system catalyzes both the hydroxylation and the epoxidation reactions. Both the hydroxylation and epoxidation activities are located in the cell-free particulate fraction precipitated between 10,000 and 40,000 x g centrifugation.

Alkenes↗
PubMedDate not supplied

Metabolism of chlorinated alkenes and alkanes as related to toxicity.

The chlorine substitution in aliphatic compounds results, by its electron attracting effect, in a destabilization in alkanes and a stabilization in alkenes. Thus, with alkanes the main pathways of metabolic transformation to reactive intermediates are radical formation by C-C break or dechlorination, or dehydrochlorination. In alkenes, the stability of the molecule increases with the number of chlorine substitutions. In the series of chlorinated ethylenes, the first step of metabolic transformation is the oxidation to electrophilic oxiranes which may be hydrolized enzymatically or non-enzymatically, react with cellular nucleophiles, or rearrange to either chlorinated aldehydes or acyl chlorides. With tetra-, 1,2-cis- and trans-di-, 1,1-di-, and monochloroethylene, the metabolites identified in in vivo experiments are identical with the thermal rearrangement products of the respective oxiranes. An important exception is found with trichloroethylene, where the thermal rearrangement product is dichloroacetyl chloride; the metabolites in vivo, however, are entirely derived from trichloroacetaldehyde (chloral). The reason for this peculiar behavior is most probably a Lewis acid catalysis by the oxidizing enzyme system. Mutagenic and carcinogenic activities in the series of chlorinated ethylenes are determined by the stability of their oxiranes, which is higher in symmetrical than in unsymmetrical chlorine substitution: the relatively unstable and unsymmetric oxiranes of trichloroethylene, 1, 1,-dichloro-, and monochloroethylene are mutagenic in the Ames test; the more stable symmetric oxiranes of tetra-, 1,2-cis- and trans-dichloroethylenes are inactive.

Animals↗
PubMed1977

The soluble methane mono-oxygenase of Methylococcus capsulatus (Bath). Its ability to oxygenate n-alkanes, n-alkenes, ethers, and alicyclic, aromatic and heterocyclic compounds.

1. Methane mono-oxygenase of Methylococcus capsulatus (Bath) catalyses the oxidation of various substituted methane derivatives including methanol. 2. It is a very non-specific oxygenase and, in some of its catalytic properties, apparently resembles the analogous enzyme from Methylomonas methanica but differs from those found in Methylosinus trichosporium and Methylomonas albus. 3. CO is oxidized to CO2. 4. C1-C8 n-alkanes are hydroxylated, yielding mixtures of the corresponding 1- and 2-alcohols; no 3- or 4-alcohols are formed. 5. Terminal alkenes yield the corresponding 1,2-epoxides. cis- or trans-but-2-ene are each oxidized to a mixture of 2,3-epoxybutane and but-2-en-1-ol with retention of the cis or trans configuration in both products; 2-butanone is also formed from cis-but-2-ene only. 6. Dimethyl ether is oxidized. Diethyl ether undergoes sub-terminal oxidation, yielding ethanol and ethanal in equimolar amounts. 7. Methane mono-oxygenase also hydroxylates cyclic alkanes and aromatic compounds. However, styrene yields only styrene epoxide and pyridine yields only pyridine N-oxide. 8. Of those compounds tested, only NADPH can replace NADH as electron donor.

Alkanes↗
PubMed1979

Microbial oxidation of gaseous hydrocarbons. II. Hydroxylation of alkanes and epoxidation of alkenes by cell-free particulate fractions of methane-utilizing bacteria.

Cell-free particulate fractions derived from methylotrophic bacteria catalyze the oxygen- and reduced nicotinamide adenine dinucleotide-dependent epoxidation of alkenes and hydroxylation of alkanes. Evidence presented indicates that the hydroxylation and epoxidation reactions are catalyzed by the same or a similar metal-containing monooxygenase.

Alkanes↗
PubMed1977

Hydration of arene and alkene oxides by epoxide hydrase in human liver microsomes.

The comparative hydration of styrene 7,8-oxide, octene 1,2-oxide, naphthalene 1,2-oxide, phenanthrene 9,10-oxide, benzo[a]anthracene 5,6-oxide, 3-methylcholanthrene 11,12-oxide, dibenzo[a,h]anthracene 5,6-oxide, and benzo[a, 7,8-, 9,10-, and 11,12-oxides to their respective dihydrodiols was investigated in microsomes from nine human autopsy livers. The substrate specificity of the epoxide hydrase in human liver microsomes was very similar to that of the epoxide hydrase in rat liver microsomes. Phenanthrene 9,10-oxide was the best substrate for the human and rat epoxide hydrases and dibenzo[a,h]anthracene 5,6-oxide and benzo[a-a)pyrene 11, 12-oxide were the poorest substrates. Plotting epoxide hydrase activity obtained with one substrate against epoxide hydrase activity for another substrate for each of the nine human livers revealed excellent correlations for all combinations of the 11 substrates studied (r = 0.87 to 0.99). The data suggest the presence in human liver of a single epoxide hydrase with broad substrate specificity. However, the results do not exclude the possible presence in human liver of several epoxide hydrases that are under similar regulatory control. These results suggest the need for further investigation to determine whether there is a safe epoxide of a drug whose in vivo metabolism is predictive of the capacity of different individuals to metabolize a wide variety of epoxides of drugs and environmental chemicals.

Alkenes↗
PubMed1975

Volatile organic components in the Skylab 4 spacecraft atmosphere.

The volatile organic components in the spacecraft cabin atmosphere of Skylab 4 were trapped on a solid adsorbent at various times during the mission. In post-flight analyses, more than 300 compounds in concentrations from less than 1 ppb up to 8000 ppb could be detected by high-resolution gas chromatography. In the samples of the 11th, 47th, and 77th day of the mission, approximately 100 components in the molecular weight range of 58 to 592 were identified by mass spectrometry. Besides components known from other environments, such as alkanes, alkenes, and alkylated aromatic hydrocarbons, components typical for the human metabolism such as ketones and alcohols were found. Other typical components in the spacecraft atmosphere are fluorocarbons (freons) and various silicone compounds, mostly normal and cyclic methylsiloxanes.

Air Pollutants↗
PubMed1979

Characterization of normal human cells by pyrolysis gas chromatography mass spectrometry.

Differentiation of normal human cells has been accomplished by pyrolysis gas chromatography mass spectrometry. Normal cells from human kidney, spleen, liver and brain tissues have been pyrolyzed and the products chromatographically separated and characterized by mass spectrometry. Molecular pyrolysis products giving rise to the characteristic pyro-mass chromatograms include, but are not limited to, alkenes, alkanes, nitriles and various ring compounds. Single ion mass chromatograms as well as multiple ion mass chromatograms have been used to explore the characteristic differences between various tissue materials. A dynamic computer methodology for comparing pyro-mass chromatograms has been developed for use in automatic identification and classification of the human cellular material.

Brain↗
PubMed1979

Synthesis of 3-hydroxy-3-phenacyloxindole analogs.

Substituted isatins and substituted acetophenones were condensed to give analogs of 3-hydroxy-3-phenacyloxindole. These alcohols were dehydrated, and the alkene was reduced. None of the products had the level of anticonvulsant activity exhibited by the parent compound.

Animals↗
PubMed1978

Microbial oxidation of methane and methanol: isolation of methane-utilizing bacteria and characterization of a facultative methane-utilizing isolate.

A methane-utilizing organism capable of growth both on methane and on more complex organic substrates as a sole source of carbon and energy, has been isolated and studied in detail. Suspensions of methane-grown cells of this organism oxidized C-1 compounds (methane, methanol, formaldehyde, formate); hydrocarbons (ethane, propane); primary alcohols (ethanol, propanol); primary aldehydes (acetaldehyde, propionaldehyde); alkenes (ethylene, propylene); dimethylether; and organic acids (acetate, malate, succinate, isocitrate). Suspensions of methanol-or succinate-grown cells did not oxidize methane, ethane, propane, ethylene, propylene, or dimethylether, suggesting that the enzymatic systems required for oxidation of these substrates are induced only during growth on methane. Extracts of methane-grown cells contained a particulate reduced nicotinamide adenine dinucleotide-dependent methane monooxygenase activity. Oxidation of methanol, formaldehyde, and primary alcohols was catalyzed by a phenazine methosulfate-linked, ammonium ion-requiring methanol dehydrogenase. Oxidation of primary aldehydes was catalyzed by a phenazine methosulfate-linked, ammonium ion-independent aldehyde dehydrogenase. Formate was oxidized by a nicotinamide adenine dinucleotide-specific formate dehydrogenase. Extracts of methane-grown, but not succinate-grown, cells contained the key enzymes of the serine pathway, hydroxypyruvate reductase and malate lyase, indicating that the enzymes of C-1 assimilation are induced only during growth on C-1 compounds. Glucose-6-phosphate dehydrogenase was induced during growth on glucose. Extracts of methane-grown cells contained low levels of enzymes of the tricarboxylic acid cycle, including alpha-keto glutarate dehydrogenase, relative to the levels found during growth on succinate.

Alcohol Oxidoreductases↗
PubMed1979

Hydroxylase regulation in Candida tropicalis grown on alkanes.

Candida tropicalis synthesizes a hydroxylase (3 to 5 nmol of product formed per minute per milligram of protein) and a cytochrome P-450 (0.10 to 0.13 nmol per milligram of protein) during growth on n-tetradecane. A three- to four-fold increase in the level of NADPH cytochrome c reductase is also observed in those cells as compared to the level of cells grown on glycerol. The most efficient inducers of the hydroxylase and of cytochrome P-450 are straight-chain alkanes having at least 10 carbon atoms. Alkenes and higher alcohols are also good inducers. There is little or no growth on ramified hydrocarbons such as pristane and on long-chain aldehydes and fatty acids. The partial inhibition of growth on decane is probably due to the denaturation of the microsomal electron carrier systems by the fatty acid formed by hydroxylation of the decane in the yeast.

Alkanes↗
PubMedDate not supplied

Reaction of glutathione with conjugated carbonyls.

1. GSH reacts with conjugated carbonyls according to the equation: GSH+R-CH=CH-COR in equilibrium R-CH(SG)-CH2-COR. The forward reaction follows second order, the reverse reaction first order kinetics. It is assumed that this reaction reflects best the ability of conjugated carbonyls to inactivate SH groups in biological systems. 2. The rate of forward reaction increases with pH approx. parallel with alphaSH. Besides OH- ions also proton donors (e.g. buffers) increase the rate. The catalytic effect of pH and buffer is interpreted in view of the reaction mechanism. 3. The equilibrium constants as well as the rate constants for forward (k1) and reverse reaction show an extreme variation depending on the carbonyl structure. Acrolein and methyl vinyl ketone (k1 = 120 and 32 mol-1 sec-1, resp.) react more rapidly than any other carbonyl to give very stable adducts (half-lives for reverse reaction 4.6 and 60.7 days, resp). Somewhat less reactive are 4-hydroxy-2-alkenals and 4-ketopentenoic acid (k1 between 1 and 3 mol-1 sec-1), but they also form very stable adducts showing half-lives between 3.4 and 19 days. All other carbonyl studied react either very slowly (e.g. citral, ethly crotonate, mesityl oxide, acrylic acid) or form very labile adducts (crotonal, pentenal, hexenal, 3-methyl-butenone). Comparing biological activities of conjugated carbonyls their reactivity towards HS (k1) and the stability of the adducts must be considered.

Aldehydes↗
PubMed1979

Purification of human liver microsomal epoxide hydrase. Differences in the properties of the human and rat enzymes.

Human liver microsomal epoxide hydrase has been highly purified to a specific activity (570 to 620 nmol/min/mg of protein) comparable to that of the rat enzyme using styrene oxide as substrate. Like the purified rat liver microsomal epoxide hydrase, the human enzyme has a minimum molecular weight of 49,000 as determined by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate and exhibits broad substrate specificity toward a variety of alkene and arene oxides. Despite these similarities, the human and rat enzymes are different proteins as judged by their immunochemical properties as well as their relative catalytic activities toward certain substrates.

Animals↗
PubMed1977

Liver microsomal epoxide hydrase.

1. The substrate specificity of membrane-bound and purified epoxide hydrase from rat liver microsomes has been studied. Both enzyme preparations catalyzed the hydration of a variety of alkene oxidase as well as arene oxides of several polycyclic aromatic hydrocarbons. 2. Unlike the membrane-bound enzyme, the rate of hydration for most of the substrates catalyzed by the purified epoxide hydrase was constant for only 1 or 2 min. The addition of dilauroyl phosphatidylcholine or heated microsomes to the incubation mixture extended the linearity of the reaction. 3. When rat liver microsomes were used as the source of the enzyme, the apparent Km values for many of the substrates were dependent on the amount of microsomes used. When purified epoxide hydrase was used as the enzyme source and benzo(a)pyrene 11,12-oxide as substrate, the apparent Km for benzo(a)pyrene 11,12-oxide was independent of enzyme concentration but dependent on added lipid concentration. Thus, in the absence of added dilauroyl phosphatidylcholine or in the presence of this lipid at a concentration below its critical micelle concentration, the observed Km for benzo(a)pyrene 11,12-oxide remained constant. However, when the lipid concentration was greater than the critical micelle concentration, the apparent Km value increased linearly with lipid concentration. These results are consistent with a model based on the partition of lipid-soluble substrate between the lipid micelle and the aqueous medium.

Animals↗
PubMed1978

Synthesis of new sulfuric derivatives of allobarbital (5,5-diallylbarbituric acid) with anti-inflammatory activity.

It was found that allyl group of alkenes Ia-Ig is transformed into 3'-sulfo-2'-sulfatopropyl or beta-methyl-beta-sulton groups in reaction of addition under action of concentrated sulfuric acid in the presence of methyl cyanide. It was stated that this reaction is competitive to the Ritter reaction. Soluble in water calcium salts IV obtained from compounds Ia and Ib exhibited strong antiinflammatory activity.

Anti-Inflammatory Agents↗
PubMed1978

Pulmonary metabolism of epoxides.

Activities of epoxide hydrase (EH) and glutathione S-transferase (GST) have been measured in pulmonary tissue from several species. On the basis of total organ activity, pulmonary tissue has less capacity than liver tissue to metabolize epoxides. Pulmonary EH and GST appear to be refractory to induction by typical agents. Rat pulmonary GST will conjugate a variety of epoxides, but K-region epoxides are metabolized at lower rates than alkene oxides. In the isolated perfused rabbit lung, benzo (a) pyrene-4,5-oxide (BPO) is metabolized by EH and GST at similar initial rates, but EH activity is lost after a few minutes, apparently owing to inadequate local substrate levels. GST from rabbit lung cytosol has been separated by chromatographic methods into six peaks of enzymic activity (toward 1-chloro-2,4-denitrobenzene). Of these peaks, all six metabolized BPO and two metabolized styrene oxide. Although EH and GST are less active in lung than in liver, pulmonary metabolism of epoxides is important because this tissue must be able to protect itself from arene oxides generated by pulmonary oxidative metabolism of polycyclic aromatic hydrocarbons.

Animals↗
PubMed1979

Competitive inhibitors of rabbit hepatic microsomal 12 alpha-steroid hydroxylase.

Rabbit hepatic microsomal 12 alpha-steroid hydroxylase which is stable to storage at -70 degrees C in the pellet form was assayed for activity with [5 alpha,6 alpha-3H2]cholestane-3 alpha,7 alpha-diol solubilized with Tween 80 since methanol was incapable of maintaining the sterol in aqueous solution. Under optimized conditions in phosphate buffer, pH 7.4, containing nicotinamide, magnesium chloride, and NADPH, the enzyme conversion appeared linear for the initial 10 min. The rate of hydroxylation was proportional to protein concentration up to 4 mg/ml. Apparent Km and Vmax were 71 microM and 323 pmol of product/mg of protein/min. Based on the known structural requirements of the enzyme system, competitive inhibitors were prepared with the C-12 position derivatized as an alkene, hydroxyl, or oxo functional group. A Dixon plot revealed that 5 alpha-cholest-11-ene-3 alpha,7 alpha,26-triol was the best inhibitor with an apparent Ki of 26 microM.

Animals↗