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  • Articles  (5)
  • Physical Chemistry  (4)
  • precursor  (1)
  • Wiley-Blackwell  (5)
  • Cell Press
  • Molecular Diversity Preservation International
  • 1975-1979  (5)
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  • Articles  (5)
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  • Wiley-Blackwell  (5)
  • Cell Press
  • Molecular Diversity Preservation International
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  • 1
    Electronic Resource
    Electronic Resource
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 6 (1977), S. 135-153 
    ISSN: 0091-7419
    Keywords: periplasmic proteins ; transport ; precursor ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The cold osmotic shock procedure releases a protein (GLPT) from the cell envelope of Escherichia coli that is related to the transport of sn-glycerol-3-phosphate in this organism. The evidence for this correlation is as follows: (1) GLPT is under the regulatory control of the glpR gene. (2) Some glpT mutants that were isolated as phosphonomycin resistant clones do not synthesize GLPT. Revertants of these mutants (growth on sn-glycerol 3-phosphate) again synthesize GLPT. (3) Some amber mutations in glpT reduce the amount of GLPT while suppressed strains produce normal amounts. (4) Transfer of a plasmid carrying the glpT genes into a strain lacking GLPT and sn-glycerol-3-phosphate transport restores both functions in the recipient. Transport and GLPT synthesis in the plasmid carrying strain are increased 2- to 3-fold over a fully induced wild-type strain, but appear to be constitutive. GLPT is a soluble protein of molecular weight 160,000 composed of 4 identical subunits. The 160,000 molecular weight complex is stable in 1% sodium dodecylsulfate at room temperature. Upon boiling in 1% sodium dodecylsulfate GLPT dissociates into its subunits. Likewise, 8 M urea at room temperature dissociates GLPT into its subunits. Dialysis of dissociated GLPT against phosphate or Tris-HCl buffer, pH 7.0, allows renaturation to the tetrameric form. The protein is acidic in nature (isoelectric point 4.4).In contrast to the typical transport-related periplasmic-binding proteins, no conditions could be found where pure GLPT exhibited binding activity toward its supposed substrate, sn-glycerol-3-phosphate.In vivo new appearance of transport activity for sn-glycerol-3-phosphate transport occurs only shortly before cell division. However, GLPT synthesis does not fluctuate during the cell cycle. The available evidence indicates a cell-division-dependent processing of GLPT in the cell envelope as a reason for the alteration in transport activity.Transport in whole cells is sensitive to the cold osmotic shock procedure, demonstrating the participation of an essential periplasmic component. However, isolated membrane vesicles that are devoid of periplasmic components, including GLPT, are fully active in sn-glycerol-3-phosphate transport. Therefore, we conclude that GLPT is essential in overcoming a diffusion barrier for sn-glycerol-3-phosphate established by the outer membrane. Attempts to isolate mutants that are transport negative in whole cells due to a defect in GLPT but are active in isolated membrane vesicles have failed so far. All GLPT mutants tested, whether or not they synthesize GLPT, are not active in isolated membrane vesicles.Iodination of whole cells with [125I] followed by osmotic shock reveals that several shock-releasable proteins including GLPT become radioactively labeled. This indicates that some portions of GLPT are accessible to the external medium.
    Additional Material: 13 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 11 (1979), S. 613-619 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The thermal decomposition of SF5O3SF5 has been investigated between 5 and 25°C. In the presence of sufficient high pressures of O2 the only products formed are SF5O2SF5 and O2: \documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm SF}_5 {\rm O}_3 {\rm SF}_5 { } \to { SF}_{5} {O}_{2} {SF}_{5} { + (}{\raise0.5ex\hbox{$\scriptstyle {1}$} \kern-0.1em/\kern-0.15em\lower0.25ex\hbox{$\scriptstyle {2}$}}{) O}_{2} {, }\Delta n{ = }{\raise0.5ex\hbox{$\scriptstyle {1}$} \kern-0.1em/\kern-0.15em \lower0.25ex\hbox{$\scriptstyle 2$}} $$\end{document} The reaction is homogeneous. Its rate is strictly first order with respect to the trioxide pressure and independent of the total pressure of the reaction products and of oxygen above a certain limiting pressure: \documentclass{article}\pagestyle{empty}\begin{document}$$ - \frac{{{\rm d}[{\rm SF}_5 {\rm O}_3 {\rm SF}_5 ]}}{{{\rm dt}}}{ = + }\frac{{{\rm d}[{\rm SF}_5 {\rm O}_2 {\rm SF}_5 ]}}{{{\rm dt}}}{ = 2}\frac{{{dp}}}{{{\rm dt}}}{ = k[SF}_{5} {O}_{3} {SF}_{5} {]} $$\end{document} The experimental results can be explained with the following mechanism: In the presence of O2 〉 100 Torr the concentration of SF5 is insignificantly small. Therefore reactions (5) and (6) do not have to be considered any more, and steps (2) and (2′) will be of no importance. From reactions (1)-(4) it follows: \documentclass{article}\pagestyle{empty}\begin{document}$$ - \frac{{d[{\rm SF}_{\rm 5} {\rm O}_{\rm 3} {\rm SF}_{\rm 5} ]}}{{dt}} = + \frac{{d[{\rm SF}_{\rm 5} {\rm O}_{\rm 2} {\rm SF}_{\rm 5} ]}}{{dt}} = k_1 \frac{{[{\rm SF}_{\rm 5} {\rm O}_{\rm 3} {\rm SF}_{\rm 5} ]}}{{1 + k'_1 (1/2k_3 k_4 )^{1/2} }}k({\rm sec}^{{\rm - 1}}) = k_1 /\left[ {1 + k'_1 \left({\frac{1}{{2k_3 k_4 }}} \right)^{1/2} } \right] = 10^{16.06 \pm 0.37} {\rm exp( - 26,000} \pm {\rm 500}\,{\rm cal)/1}{\rm .987 }T $$\end{document}The numerical value of the factor [1 + (k′12/2k3k4)1/2] is small. It can be estimated that E3 ≃ 2 ± 1 kcal; therefore, E - E1 ≤ 1 kcal, and D (SF5O—O2SF5) = (26 - 1) ± 1.0 kcal.
    Additional Material: 3 Tab.
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 10 (1978), S. 111-116 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The thermal decomposition of F5SOOSF5, P, in the presence of CO has been investigated between 130.1° and 161.9°C at total pressures between 50 and 600 torr. The reaction is homogeneous, and the only final products formed are CO2 and S2F10. The rate of reaction is proportional to the pressure of P. The partial pressures of CO and O2 and the total pressure have no influence on the course of reaction: \documentclass{article}\pagestyle{empty}\begin{document}$$ - \frac{{d\left[P \right]}}{{dt}} = k\left[P \right] $$\end{document}The results are explained by the following mechanism:
    Additional Material: 1 Tab.
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 10 (1978), S. 1215-1223 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Using the ECR technique the electron scavenging properties of the halomethanes CHF3, CHClF2, and CHCl2F were investigated. A brief discussion is given on the evaluation of experimental data for inefficient polar scavengers. Absolute attachment rate constants were obtained from the decrease of the cyclotron resonance signal upon addition of the above scavengers. For the molecules CHF3 and CHCl2F the activation energies for the capture processes are given. Possible capture mechanisms are discussed.
    Additional Material: 3 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 11 (1979), S. 1089-1096 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The thermal decomposition of SF5O3SF5 in the presence of CO has been investigated between -9.8°C and + 9.9°C. Besides traces of S2F10, equimolecular amounts of SF5O2SF5 and CO2 are formed. \documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm SF}_{\rm 5} {\rm O}_{\rm 3} {\rm SF}_{\rm 5} {\rm + CO } \to {\rm SF}_{\rm 5} {\rm O}_{\rm 2} {\rm SF}_{\rm 5} {\rm + CO}_{\rm 2}{\rm,}\Delta _n {\rm = 0} $$\end{document} The reaction is homogeneous. Its rate is proportional to the pressure of the trioxide and in dependent of the total pressure, the pressure of inert gases and of carbon monoxide: \documentclass{article}\pagestyle{empty}\begin{document}$$ - {\rm }\frac{{d[{\rm SF}_5 {\rm O}_{\rm 3} {\rm SF}_5 ]}}{{dt}}{\rm = +}\frac{{d[{\rm SF}_5{\rm O}_{\rm 2} {\rm SF}_5 }}{{dt}} = {\rm}k[{\rm SF}_5 {\rm O}_{\rm 3}{\rm SF}_5 ] $$\end{document} where k = k1∞ = 1016.32±0.40 exp(-25,300 ± 500 cal)/RT sec-1. Consequently, \documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm D}_{{\rm SF}_{\rm 5} {\rm O - O}_{\rm 2} {\rm SF}_{\rm 5}} {\rm =}25.3{\rm}\pm {\rm 0}{\rm .5 kcal} $$\end{document} In the presence of oxygen a sensitized CO2 formation is observed. A mechanism is given which explains the experimental results.
    Additional Material: 1 Ill.
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