Formation mechanism of 2,6-dimethyl-2,6-octadienes from thermal decomposition of linalyl beta-D-glucopyranoside.
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Thermally decomposed products of (+/-)-linalyl beta-D-glucoside were analyzed by GC and GC/MS. 2,6-dimethyl-2,6-octadienes produced by mild pyrolysis of linalyl beta-D-glucopyranoside under a vacuum were detected and characterized by MS and NMR spectroscopy. This suggests that 2,6-dimethyl-2,6-octadienes are produced during thermal decomposition of the glucoside via proton transfer from the anomeric position to C-6 in the aglycon moiety. A stable isotope labeling experiment directly indicated the new reaction mechanism. (+info)
Nanosecond dynamics of a mimicked membrane-water interface observed by time-resolved stokes shift of LAURDAN.
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We studied the dipolar relaxation of the surfactant-water interface in reverse micelles of AOT-water in isooctane in the nanosecond and subnanosecond time ranges by incorporating the amphipathic solvatochromic fluorescent probes LAURDAN and TOE. A negative component was observed in the fluorescence decays in the red edge of the emission spectrum-the signature of an excited state reaction-with LAURDAN but not for TOE. The deconvolution of the transient reconstructed spectra of LAURDAN based on a model constructed by adding together three log-normal Gaussian equations made it possible to separate the specific dynamic solvent response from the intramolecular excited state reactions of the probe. The deconvoluted spectrum of lowest energy displayed the largest Stokes shift. This spectral shift was described by unimodal kinetics on the nanosecond timescale, whereas the relaxation kinetics of water-soluble probes have been reported to be biphasic (on the subnanosecond and nanosecond timescales) due to the heterogeneous distribution of these probes in the water pool. Most of this spectral shift probably resulted from water relaxation as it was highly sensitive to the water to surfactant molar ratio (w(0)) (60-65 nm at w(0) = 20-30). A small part of this spectral shift (9 nm at w(0) = 0) probably resulted from dipolar interaction with the AOT polar headgroup. The measured relaxation time values were in the range of the rotational motion of the AOT polar headgroup region as assessed by LAURDAN and TOE fluorescence anisotropy decays. (+info)
Propane and n-butane oxidation by Pseudomonas putida GPo1.
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Propane and n-butane inhibit methyl tertiary butyl ether oxidation by n-alkane-grown Pseudomonas putida GPo1. Here we demonstrate that these gases are oxidized by this strain and support cell growth. Both gases induced alkane hydroxylase activity and appear to be oxidized by the same enzyme system used for the oxidation of n-octane. (+info)
Display of a thermostable lipase on the surface of a solvent-resistant bacterium, Pseudomonas putida GM730, and its applications in whole-cell biocatalysis.
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BACKGROUND: Whole-cell biocatalysis in organic solvents has been widely applied to industrial bioprocesses. In two-phase water-solvent processes, substrate conversion yields and volumetric productivities can be limited by the toxicity of solvents to host cells and by the low mass transfer rates of the substrates from the solvent phase to the whole-cell biocatalysts in water. RESULTS: To solve the problem of solvent toxicity, we immobilized a thermostable lipase (TliA) from Pseudomonas fluorescens on the cell surface of a solvent-resistant bacterium, Pseudomonas putida GM730. Surface immobilization of enzymes eliminates the mass-transfer limitation imposed by the cell wall and membranes. TliA was successfully immobilized on the surface of P. putida cells using the ice-nucleation protein (INP) anchoring motif from Pseudomonas syrinage. The surface location was confirmed by flow cytometry, protease accessibility and whole-cell enzyme activity using a membrane-impermeable substrate. Three hundred and fifty units of whole-cell hydrolytic activity per gram dry cell mass were obtained when the enzyme was immobilized with a shorter INP anchoring motif (INPNC). The surface-immobilized TliA retained full enzyme activity in a two-phase water-isooctane reaction system after incubation at 37 degrees C for 12 h, while the activity of the free form enzyme decreased to 65% of its initial value. Whole cells presenting immobilized TliA were shown to catalyze three representative lipase reactions: hydrolysis of olive oil, synthesis of triacylglycerol and chiral resolution. CONCLUSION: In vivo surface immobilization of enzymes on solvent-resistant bacteria was demonstrated, and appears to be useful for a variety of whole-cell bioconversions in the presence of organic solvents. (+info)
Analysis of ingested material and urine by GC-MS and 1H NMR spectroscopy: poisoning of an adult with adulterated soda.
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The purpose of this work is to characterize chemical compounds added to an ingested soda by (1)H nuclear magnetic resonance ((1)H NMR) spectroscopy and by gas chromatography-mass spectrometry in the electron impact mode. A second point was to highlight possible metabolic disturbances by considering urinary profile. Without any pretreatment, dimethylphtalate, 2-butanone, and 2,2,4-trimethylpentanediol diisobutyrate were found in the adulterated soda. Quantitative analysis was performed by relative integration of peak areas. Huge quantities of 2,2,4-trimethylpentanediol diisobutyrate and dimethylphtalate were found in the oily layer. 2-Butanone, which is miscible in water, was found in the two phases as well as small quantities of dimethylphtalate. The urine sample was collected on hospital admission and was also analyzed by (1)H NMR spectroscopy. The major abnormal compound found was 1,2-propanediol. Other disturbances concerned endogenous metabolites such as 2-ketoglutaric acid, lactic acid, and betaine. (+info)
Utility of 1-octanol/octane mixed solvents for the solvent extraction of aluminum(III), gallium(III), and indium(III) with 8-quinolinol.
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Using 1-octanol/octane mixed solvents, the extraction of aluminum(III), gallium(III) and indium(III) with 8-quinolinol was carried out at 25 degrees C. The formation constants of the respective metal(III) 8-quinolinolates in the aqueous phase and their partition constants between the mixed solvents and water were determined based on an analysis of the extraction equilibria. The relationship between the partition constants of 8-quinolinol and its complexes was analyzed by the regular solution theory. The molar volumes of aluminum(III), gallium(III) and indium(III) 8-quinolinolates, calculated from the present results, suggest that the electrostriction effect functions in complex forming. It has been found that octane/1-octanol mixed solvents were available not only for the extraction of metal ions, but also for determining the formation constants of these metal 8-quinolinolates in the aqueous phase and their partition constants. (+info)
Production of alpha, omega-alkanediols using Escherichia coli expressing a cytochrome P450 from Acinetobacter sp. OC4.
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Our biotransformation using Escherichia coli expressing a cytochrome P450 (CYP) belonging to the CYP153A family from Acinetobacter sp. OC4 produced a great amount of 1-octanol (2,250 mg per liter) from n-octane after 24 h of incubation. This level of production is equivalent to the maximum level previously achieved in biotransformation experiments of alkanes. In addition, the initial production rate of 1-octanol was maintained throughout the entire incubation period. These results indicate that we have achieved the functional and stable expression of a CYP in E. coli for the first time. Further, our biotransformation system showed alpha,omega-diterminal oxidation activity of n-alkanes, and a large amount of 1,8-octanediol (722 mg per liter) was produced from 1-octanol after 24 h of incubation. This is the first report on the bioproduction of alpha,omega-alkanediols from n-alkanes or 1-alkanols. (+info)
Synthesis and activity of a potent, specific azabicyclo[3.3.0]-octane-based DPP II inhibitor.
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A cell permeable DPP II [also known as DPP2, DPP7, and quiescent cell proline dipeptidase (QPP)] inhibitor has been synthesized. The azabicyclo[3.3.0]octane-based inhibitor is potent and selective and elicits very similar quiescent lymphocyte death to previously characterized inhibitors that are not as selective. (+info)