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PubMed1989

Effect of propan-2-ol on enzymic and structural properties of elongation factor G.

Elongation factor G (EF-G) can support a GTPase activity in vitro even in the absence of ribosomes when propan-2-ol is present [GTPasep; De Vendittis, Masullo & Bocchini (1986) J. Biol. Chem. 261, 4445-4450]. In the present work the GTPasep activity of EF-G was further studied by investigating (i) the effect of ionic environment on GTPasep and (ii) the influence of propan-2-ol on the molecular structure of EF-G as determined by fluorescence and c.d. measurements. In the presence of 1-300 mM univalent cations (M+) alone, no detectable GTPasep activity was measured; however, in the presence of 1 mM-Mg2+ a considerable stimulation was observed at 40 mM-Li+ or 75 mM-NH4+. Among bivalent cations (M2+), 1 mM-Sr2+, 2-5 mM-Ca2+ and 1 mM-Ba2+ were the most effective, but, in the presence of 75 mM-NH4+, Mg2+ and Mn2+ became the most efficient, whereas the stimulation by other M2+ species was considerably decreased. C.d. measurements showed that the alcohol increased the mean molar residue ellipticity of EF-G at 285 nm, but not at 220 nm. As estimated from fluorescence measurements, in the presence of 20% (v/v) propan-2-ol the value of the dissociation constant of the complex formed between EF-G and 8-anilino-1-naphthalene-sulphonate decreased from 8 to 5 microM; similarly, the number of binding sites on EF-G for the fluorescent probe decreased from 13 to 6. Finally, the alcohol enhanced the quenching of the intrinsic fluorescence of EF-G caused by either acrylamide or KI. The data support the hypothesis that propan-2-ol induces moderate conformational changes of EF-G that make the catalytic centre accessible to the substrate even in the absence of ribosomes. Kinetics of GTPasep studied at different temperatures did not reveal additional structural changes of EF-G occurring with time or temperature.

1-Propanol↗
PubMed2002

The crystal structure of coenzyme B12-dependent glycerol dehydratase in complex with cobalamin and propane-1,2-diol.

Recombinant glycerol dehydratase of Klebsiella pneumoniae was purified to homogeneity. The subunit composition of the enzyme was most probably alpha 2 beta 2 gamma 2. When (R)- and (S)-propane-1,2-diols were used independently as substrates, the rate with the (R)-enantiomer was 2.5 times faster than that with the (S)-isomer. In contrast to diol dehydratase, an isofunctional enzyme, the affinity of the enzyme for the (S)-isomer was essentially the same or only slightly higher than that for the (R)-isomer (Km(R)/Km(S) = 1.5). The crystal structure of glycerol dehydratase in complex with cyanocobalamin and propane-1,2-diol was determined at 2.1 A resolution. The enzyme exists as a dimer of the alpha beta gamma heterotrimer. Cobalamin is bound at the interface between the alpha and beta subunits in the so-called 'base-on' mode with 5,6-dimethylbenzimidazole of the nucleotide moiety coordinating to the cobalt atom. The electron density of the cyano group was almost unobservable, suggesting that the cyanocobalamin was reduced to cob(II)alamin by X-ray irradiation. The active site is in a (beta/alpha)8 barrel that was formed by a central region of the alpha subunit. The substrate propane-1,2-diol and essential cofactor K+ are bound inside the (beta/alpha)8 barrel above the corrin ring of cobalamin. K+ is hepta-coordinated by the two hydroxyls of the substrate and five oxygen atoms from the active-site residues. These structural features are quite similar to those of diol dehydratase. A closer contact between the alpha and beta subunits in glycerol dehydratase may be reminiscent of the higher affinity of the enzyme for adenosylcobalamin than that of diol dehydratase. Although racemic propane-1,2-diol was used for crystallization, the substrate bound to glycerol dehydratase was assigned to the (R)-isomer. This is in clear contrast to diol dehydratase and accounts for the difference between the two enzymes in the susceptibility of suicide inactivation by glycerol.

Binding Sites↗
PubMed1972

Metabolism of Propane, n-Propylamine, and Propionate by Hydrocarbon-Utilizing Bacteria.

Studies were conducted on the oxidation and assimilation of various three-carbon compounds by a gram-positive rod isolated from soil and designated strain R-22. This organism can utilize propane, propionate, or n-propylamine as sole source of carbon and energy. Respiration rates, enzyme assays, and (14)CO(2) incorporation experiments suggest that propane is metabolized via methyl ketone formation; propionate and n-propylamine are metabolized via the methylmalonyl-succinate pathway. Isocitrate lyase activity was found in cells grown on acetate and was not present in cells grown on propionate or n-propylamine. (14)CO(2) was incorporated into pyruvate when propionate and n-propylamine were oxidized in the presence of NaAsO(2), but insignificant radioactivity was found in pyruvate produced during the oxidation of propane and acetone. The n-propylamine dissimilatory mechanism was inducible in strain R-22, and amine dehydrogenase activity was detected in cells grown on n-propylamine. Radiorespirometer and (14)CO(2) incorporation studies with several propane-utilizing organisms indicate that the methylmalonyl-succinate pathway is the predominant one for the metabolism of propionate.

Journal Article↗
PubMed1983

The metabolism of 1-phenyl-2-(N-methyl-N-benzylamino)propane (benzphetamine) in vitro in rat.

The metabolism of 1-phenyl-2-(N-benzylamino)propane (benzphetamine) in vitro was studied using rat-liver microsomes. Five metabolites were isolated from the incubation mixture and identified as 1-phenyl-2-(N-benzylamino)propane (benzylamphetamine), (1-(p-hydroxyphenyl)-2-(N-methyl-N-benzylamino)propane, 1-(p-hydroxyphenyl)-2-(N-benzylamino)propane, methamphetamine and amphetamine. This metabolism in vitro was compared with that in vivo which was reported previously. The formation of all five metabolites were catalysed by liver microsomes supplemented with NADPH and O2, and inhibited by either SKF 525-A or CO. N-Demethylation was inhibited by either 2-methyl-1,2-bis-(3-pyridyl)-1-propanone (metyrapone) or n-octylamine, while aromatic hydroxylation was inhibited by 7,8-benzoflavone and N-debenzylation was depressed by all these inhibitors. N-Demethylation was enhanced by pretreatment of rats with phenobarbitone, while aromatic hydroxylation was induced by pretreatment with 3-methylcholanthrene, and N-debenzylation was Induced by pretreatment with either phenobarbitone or 3-methylcholanthrene. These data suggested that the metabolism of benzphetamine was mediated by three slightly different enzyme systems.

Amphetamines↗
PubMed2006

Auto-ignition and upper explosion limit of rich propane-air mixtures at elevated pressures.

The auto-ignition limits of propane-air mixtures at elevated pressures up to 15 bar and for concentrations from 10 mol% up to 70 mol% are investigated. The experiments are performed in a closed spherical vessel with a volume of 8 dm3. The auto-ignition temperatures decrease from 300 degrees C to 250 degrees C when increasing the pressure from 1 bar to 14.5 bar. It is shown that the fuel concentration most sensitive to auto-ignition depends on initial pressure. A second series of experiments investigates the upper flammability limit of propane-air mixtures at initial temperatures up to 250 degrees C and pressures up to 30 bar near the auto-ignition area. Finally the propane auto-oxidation is modelled using several detailed kinetic reaction mechanisms and these numerical calculations are compared with the experimental results.

Air↗
PubMed2006

Long-term aerobic cometabolism of a chlorinated solvent mixture by vinyl chloride-, methane- and propane-utilizing biomasses.

The aerobic cometabolic biodegradation of a mixture of chlorinated aliphatic hydrocarbons (CAHs) including vinyl chloride (VC), cis- and trans-1,2-dichloroethylene (cis-DCE, trans-DCE), trichloroethylene (TCE), 1,1,2-trichloroethane (1,1,2-TCA) and 1,1,2,2-tetrachloroethane (1,1,2,2-TeCA) was investigated at both 25 and 17 degrees C by means of bioaugmented and non-bioaugmented sediment-groundwater slurry microcosm tests. The goals of the study were (i) to study the long-term aerobic biodegradation of a CAH mixture including a high-chlorinated solvent (1,1,2,2-TeCA) generally considered non-biodegradable in aerobic conditions; (ii) to investigate the efficacy of bioaugmentation with two types of internal inocula obtained from the indigenous biomass of the studied site; (iii) to identify the CAH-degrading bacteria. VC, methane and propane were utilized as growth substrates. The non-bioaugmented microcosms were characterized, at 25 degrees C, by an average 18-day lag-time for the direct metabolism of VC (accompanied by the cometabolism of cis- and trans-DCE) and by long lag-times (36-264 days) for the onset of methane or propane utilization (associated with the cometabolism of the remaining CAHs). In the inoculated microcosms the lag-phases for the onset of growth substrate utilization and CAH cometabolism were significantly shorter (0-15 days at 25 degrees C). Biodegradation of the 6-CAH mixture was successfully continued for up to 410 days. The low-chlorinated solvents were characterized by higher depletion rates. The composition of the microbial consortium of a propane-utilizing microcosm was determined by 16s rDNA sequencing and phylotype analysis. To the best of our knowledge, this is the first study that documents the long-term aerobic biodegradation of 1,1,2,2-TeCA.

Aerobiosis↗
PubMed1998

Death during deliberate propane inhalation.

Propane gas is used as a fuel and very rarely it is abused by young people in Greece. In this paper, we report a case of abuse of propane inhalation that resulted in accidental death. The determination of propane in autopsy samples was done by headspace gas chromatography and semiquantitation in liver, blood and the contents of the plastic bag through which the gas was diffused, which proved to be lethal.

Administration, Inhalation↗
PubMed2003

The HPLC determination of propane-1,2,3-triyl trinitrite and impurities: (2RS)-3-hydroxypropane-1,2-diyl dinitrate and 2-hydroxypropane-1,3-diyl dinitrate in ointment.

A HPLC method for determination of propane-1,2,3-triyl trinitrate and impurities: (2RS)-3-hydroxypropane-1,2-diyl dinitrate and 2-hydroxypropane-1,3-diyl dinitrate ointment was developed. The conditions for good separation of constituents, while avoiding vehiculum interference were established. The results feature of high accuracy and good precision. For individual constituents R.S.D. is ranged from 0.7 to 9.9%, while recovery was 100.1% for propane-1,2,3-triyl trinitrate and 95.1-99.0% for impurities. It has been found that propane-1,2,3-triyl trinitrate used in medicine in the form of ointment contains such impurities which can be identified and quantified at relatively low concentrations of 70 ng ml(-1).

Chromatography, High Pressure Liquid↗
PubMedDate not supplied

Quantitative determination of n-propane, iso-butane, and n-butane by headspace GC-MS in intoxications by inhalation of lighter fluid.

This report describes a fully elaborated and validated method for quantitation of the hydrocarbons n-propane, iso-butane, and n-butane in blood samples. The newly developed analytical procedure is suitable for both emergency cases and forensic medicine investigations. Its practical applicability is illustrated with a forensic blood sample after acute inhalative intoxication with lighter fluid; case history and toxicological findings are included. Identification and quantitation of the analytes were performed using static headspace extraction combined with gas chromatography-mass spectrometry. In order to reconcile the large gas volumes injected (0.5 mL) with the narrowbore capillary column and thus achieve preconcentration, cold trapping on a Tenax sorbent followed by flash desorption was applied. Adequate retention and separation were achieved isothermally at 35 degrees C on a thick-film capillary column. Sample preparation was kept to a strict minimum and involved simply adding 2.5 microL of a liquid solution of 1,1,2-trichlorotrifluoroethane in t-butyl-methylether as an internal standard to aliquots of blood in a capped vial. Standards were created by volumetric dilution departing from a gravimetrically prepared calibration gas mixture composed of 0.3% of n-propane, 0.7% of iso-butane, and 0.8% of n-butane in nitrogen. In the forensic blood sample, the following concentrations were measured: 90.0 microg/L for n-propane, 246 microg/L for iso-butane, and 846 microg/L for n-butane.

Administration, Inhalation↗
PubMed1998

Propane-associated autoerotic fatalities.

We describe 3 unusual autoerotic fatalities in which propane gas was used to induce hypoxia. To our knowledge, these are the first cases of their kind to be reported and described in depth, although brief references to similar cases have appeared. The case histories of 3 white males, aged 22, 42, and 62 years, are described with emphasis on the scene and circumstances and the identification of propane from autopsy materials. In one case, unusual paraphilia and multiple foreign bodies in the rectum were noted. These 3 cases illustrate an unusual form of autoerotic practice in which hypoxia is induced by propane inhalation, unlike the usual neck compression that has been previously described in depth. The importance of scene reconstruction and an awareness of this phenomenon is stressed.

Administration, Inhalation↗
PubMedDate not supplied

The protection against and treatment of a liquid propane freeze injury: an experimental model.

Liquid propane causes a severe, deep thermal injury in unprotected tissue. Delayed surgical intervention, as for thermal burns, has been the gold standard of treatment. An animal model of liquid-propane injury was devised to document injury, to demonstrate a better method of protection, and to define an appropriate management protocol. Twenty-eight rats were classified into four groups: unprotected tissue (n = 8), skin covered with wool (n = 8), skin covered with Neoprene (Wm. H. Horn & Brothers Inc., Philadelphia, Pa.) (n = 8), and skin covered with wool plus Neoprene (n = 4). Each group was subdivided into two exposure times: 6 seconds and 30 seconds. The mean temperatures +/- standard error of the mean of the various tissue levels initially and at 6 and 30 seconds of exposure were determined. Histologic examination demonstrated that full-thickness tissue necrosis occurred in unprotected and wool-covered tissue. Areas that were covered with Neoprene showed intact skin and subcutaneous tissue with underlying muscle necrosis. Examination of the tissue that was covered with wool plus Neoprene showed no histologic damage. There was no sign of tissue regeneration at the wound periphery, and there was no histologic difference in any group, whether the examination took place at 1 or 5 days after injury. This study demonstrated that the best form of protection appears to be a wool glove liner covered with a Neoprene glove. The histologic evidence suggests that a liquid-propane injury to unprotected tissue should be managed aggressively with early excision and grafting.

Animals↗
PubMed1981

A freeze-etch electron microscopic study of liquid propane jet-frozen human erythrocyte membranes.

Freeze-etch electron micrographs of haemolysing erythrocytes and isolated erythrocyte membranes frozen using a liquid propane jet-freezer reveal fracture faces very different from those seen after conventional freezing by dipping the specimens into partly solidified Freon 22. Instead of the rather smooth extracellular fracture faces found after conventional specimen freezing, extracellular fracture faces exhibiting large amounts of fibre-like structures are seen after liquid propane jet-freezing of these specimens. No such structures were found in normal red blood cells. When isolated erythrocyte membranes are frozen under conditions favouring spectrin-actin release, freeze-etch micrographs reveal an apparent continuity between the fibre-like structures on the extracellular fracture face and the long fibre-like structures which extent from the protoplasmic surface of the erythrocyte membrane. These results suggest that liquid propane jet-freezing is capable of revealing a structural difference between the membrane of haemolysing and nonhaemolysed red blood cells, and that this difference is related to the fibrous, peripheral proteins of the membrane.

Erythrocyte Membrane↗
PubMed1964

CELLULAR LIPIDS OF A NOCARDIA GROWN ON PROPANE AND N-BUTANE.

Lipid fractions of propane- and n-butane-grown nocardial cells each contain a chloroform-soluble, ether-insoluble polymer not observed previously in liquid n-alkane-grown cells. The polymer in propane-grown cells is poly-beta-hydroxybutyrate. The polymer in n-butane-grown cells apparently contains unsaturation in the molecule, and is identified tentatively as a co-polymer of beta-hydroxybutyric and beta-hydroxybutenoic (specifically 3-hydroxy 2-butenoic) acids. The other major component of the lipid fraction consists of triglycerides containing principally palmitic and stearic acids. There seems to be little qualitative distinction in the glycerides of propane- or n-butane-grown cells. Oxidative assimilation of n-butane is described.

Butanes↗
PubMed1994

Dehalogenation by Mycobacterium vaccae JOB-5: role of the propane monooxygenase.

Mycobacterium vaccae JOB-5 has an inducible propane monooxygenase that has been implicated in the catabolism of most major groundwater pollutants including trichloroethylene. Propane-grown cells are also induced for the dehalogenation of 1-chlorobutane and other chloroalkanes. 1-Chlorobutane is oxidized to 2-butanol, indicating that subterminal oxidation of 1-chlorobutane resulted in a concomitant release of the chloride. Nonproliferating suspensions of M. vaccae induced for the propane monooxygenase can dehalogenate a variety of chlorinated hydrocarbons including monochlorinated alcohols, dichlorinated short chain alkanes, and several multiple-substituted compounds including trichloroethylene. The results indicate that M. vaccae JOB-5 has a monooxygenase of broad specificity that can dehalogenate an array of halogenated hydrocarbons.

Biodegradation, Environmental↗
PubMed1985

Study on the metabolism of volatile hydrocarbons in mice--propane, n-butane, and iso-butane.

A study was conducted to establish whether volatile hydrocarbons, such as propane, n-butane and iso-butane, are metabolized in mice or not. In mice having inhaled these gases, isopropanol and acetone were yielded from propane, sec-butanol and methyl ethyl ketone from n-butane, and tert-butanol from iso-butane as the respective metabolites. In addition, liver microsomes were found to contain the enzymic system participating in these metabolisms. In vitro reactions with liver microsomes produced isopropanol from propane, sec-butanol from n-butane, and tert-butanol from iso-butane. It was assumed that hydrocarbons were first converted to (omega-1)-alcohols by microsomal enzyme system and then to corresponding ketones by alcohol dehydrogenase.

Alcohol Oxidoreductases↗
PubMed1992

Warehouse workers' headache. Carbon monoxide poisoning from propane-fueled forklifts.

We reviewed over 220 cases of acute carbon monoxide (CO) poisoning and now report on 17 patients whose poisoning occurred from the indoor use of propane-fueled forklifts. All patients in this series presented with neurologic symptoms or persistent headache and were given hyperbaric oxygen to resolve their symptomatology. We investigated the concentration of CO in the exhaust emissions of 12 propane-fueled forklifts used in various workplaces in our location. The average CO concentration in the exhaust during engine idling was 36,000 parts per million (3.6%). This value decreased slightly to 30,000 ppm (3.0%) at working engine speed. Measurements of exhaust flow indicate CO production rates of approximately 60 liters per minute at working engine speed. These quantities of CO constitute a significant occupational exposure risk to workers using propane-fueled forklifts in unventilated indoor environments.

Acute Disease↗
PubMed1984

Propane and tetradecane as carbon sources for in vitro cultivation of Mycobacterium lepraemurium in a liquid medium (a preliminary communication).

Three strains of host grown Mycobacterium lepraemurium and five strains of Mycobacterium lepraemurium, grown on egg yolk medium, were inoculated into propane-tetradecane media. The media contained in one litre distilled water: KH2PO4, 7 g, Na2HPO4, 0.5 g, (NH4)2SO4, 2 g, MgSO4, 0.1 g, ferric ammonium citrate, 20 mg, and yeast extract (Difco), 0.1 g. Tetradecane 0.1 ml was added to each tube containing 20 ml of the medium. Media were sterilized in the autoclave. Following inoculation with the bacilli, the cultures were bubbled aseptically with 99% purity propane gas for 10 s. When incubated at 32 degrees C, logarithmic growth rate was counted in the cultures. Bacilli were strongly acid-fast. Growth occurred at the interface of the tetradecane oil and water as a thin weil, developing into a one to three millimeter thick emulsion in two to three months. Cultures were transferred into fresh media at two to three month intervals. Growth pattern in the subcultures were indistinguishable from the growth in the primary cultures. The cultures did not grow on Löwenstein-Jensen or in Dubos media, but produced the characteristic disease of murine leprosy when injected subcutaneously into mice. Bacilli isolated from the subcutaneous lepromas of mice were again cultivable in the propane-tetradecane medium, but not on Löwenstein-Jensen or in Dubos.

Alkanes↗
PubMed1994

Asphyxial suicide by propane inhalation and plastic bag suffocation.

A 26-year-old male committed suicide by inducing asphyxia using a combination of plastic bag suffocation and propane-gas inhalation. This method has been reported in the literature, but it remains unusual. Autopsy findings were consistent with a hypoxic event, and blood, brain, and lung tissue tested positive for propane by gas chromatography. Propane, while possessing some narcotic properties, causes death primarily by displacing oxygen in the atmosphere with resultant asphyxia.

Adult↗