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  • 81.20.Lb  (1)
  • Alcaligenes eutrophus  (1)
  • Analytical Chemistry and Spectroscopy  (1)
  • 1
    ISSN: 1432-072X
    Keywords: Key words Poly-3-hydroxybutyrate ; Washed cells ; Alcaligenes eutrophus ; Citrate synthase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Washed cells prepared from carbon-limited continuous cultures of Alcaligenes eutrophus synthesised poly-3-hydroxybutyrate (PHB) rapidly when supplied with glucose, dl-lactate or l-lactate. Unlike growing cultures, washed cells excreted significant amounts of pyruvate. The combined rates of PHB production (qPHB) and pyruvate excretion (qPyr) were linearly related to the rate of carbon substrate utilisation (qS), showing that washed cells behaved similarly to growing cultures when corrected for the absence of non-PHB biomass production. The addition of formate (as a potential source of NADH and/or ATP) significantly stimulated both qPHB and qPyr, but slightly decreased qS and substantially decreased the flux of carbon through the tricarboxylic acid cycle (qTCA). Citrate synthase activity of broken cells was inhibited by physiological concentrations of NADH, but not of ATP, in a manner that was not reversible by AMP. Citrate synthase was purified and shown to be a “large” form of the enzyme (M r 227,000), comprising a single type of subunit (M r 47,000) as found in several other gram-negative aerobes. The potential role of citrate synthase in the regulation of PHB production via its ability to control carbon flux into the tricarboxylic acid cycle is discussed.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1434-6079
    Keywords: 82.65.Jv ; 81.20.Lb
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We present preliminary evidence for catalytic activity by unsupported mixed metal oxide nanocrystalline materials. The results of this study show that a nanophase form of Li-MgO has begun to exhibit catalytic activity by 300 °C. This is at least 200 degrees below the temperature at which conventional Li-MgO catalysts exhibit comparable activity. Furthermore, at higher temperatures, the same nanophase composition shows enhanced activities and somewhat improved hydrocarbon selectivities over conventional Li-MgO catalysts.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Fast atom bombardment (FAB) and collisional activation dissociation (CAD) mass-analysed ion kinetic energy (MIKE) spectra have confirmed the structures of retinyl phosphate (Ret-P), retinyl phosphate mannose (Ret-P-Man) and guanosine 5′-diphospho-D-mannose (GDP-Man). Ret-P-Man was made in vitro while Ret-P and GDP-Man were chemically synthesized. Positive ion FAB mass spectrometry of Ret-P showed an observable short-lived spectrum with a mass ion at m/z 367 [M + H]+, and a major fragment ion at m/z 269 [M+H—H3PO4]+. Negative ion FAB mass spectrometry of Ret-P showed a strong stable spectrum with a parent ion at m/z 365 [M—H]-, a glycerol (G) adduct ion at m/z 457 [M—H+G]- and a dimer ion at m/z 731 [2M—H]-. GDP-Man showed an intense spectrum with parent ion at m/z 604 [M—H]- and cationized species at m/z 626 [M+Na-2H]- and 648 [M+2Na-3H]-. Negative ion FAB mass spectrometry of Ret-P-Man showed a parent ion at m/z 527 [M—H]- and a fragment ion at m/z 259 [C6H12PO9]-. The CAD-MIKE spectra showed structurally significant fragment ions at m/z 442 and 361 for the [M—H]- ion of GDP-Man, and at m/z 509, 406, 364 and 241 for the [M—H]- ion of Ret-P-Man. FAB and CAD-MIKE spectra have been applied successfully to confirm the structure of Ret-P-Man made in vitro from Ret-P and GDP-Man.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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