Netsu Sokutei
Online ISSN : 1884-1899
Print ISSN : 0386-2615
ISSN-L : 0386-2615
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Volume 35, Issue 3
Displaying 1-5 of 5 articles from this issue
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Journal
  • Calorimetric Analysis of the Effects of Soil Stress Compound on Soil-Microbial Activity － Suppressive Effects of Sodium Chloride on Glucose Assimilation －
    Akiyo K. Sakamiya, Saki Kondo, Hideo Miyake, Keishi Senoo, Akiyoshi Ta ...
    2008 Volume 35 Issue 3 Pages 124-130
    Published: June 30, 2008
    Released on J-STAGE: November 20, 2022
    DOIhttps://doi.org/10.11311/jscta.35.3_124
    JOURNAL FREE ACCESS
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    Process of glucose assimilation by soil microbes and stressing effect of sodium chloride on the assimilation were quantitatively analyzed by a calorimetric method. One-tenth mmol glucose was added to 10 g of paddy, upland, and orchard soils in the absence and presence of various concentrations of sodium chloride, and the assimilation heat was recorded at 25 ºC. The heat-evolution curves were successfully analyzed on the basis of the Gompertz model. The effects of sodium chloride on the assimilation were evaluated by measuring the change in Gompertz parameters. Among the parameters, the time T1/2 at which half of the total heat evolution completed, and the time M at which the heat-evolution rate reaches to the maximum were suitable for accurate evaluation of the inhibitory effects of sodium chloride. The 50 % inhibitory concentration Ki of sodium chloride for the paddy, upland, and orchard soils were evaluated to be 3.9, 3.5, and 6.7 %, respectively, and the minimum inhibitory concentration MIC were 6.9, 6.7, and 12 %, respectively. This novel method can be a standard one for evaluating soil pollution and remediation using assimilation activity of microorganisms including nonculturable ones as a probe.
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Review
  • Thermostability and Redox Activity of Cytochrome c
    Yasuhiko Yamamoto, Hulin Tai
    2008 Volume 35 Issue 3 Pages 131-139
    Published: June 30, 2008
    Released on J-STAGE: November 20, 2022
    DOIhttps://doi.org/10.11311/jscta.35.3_131
    JOURNAL FREE ACCESS
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    Understanding the molecular mechanisms responsible for regulation of the redox potentials (Em) of proteins is a problem of immense fundamental and practical importance. Cytochromes c (cyts c), in which heme Fe is coordinated to His side chain imidazole N and Met side chain S atoms as axial ligands at the redox center, are some of the best characterized redox active proteins. Homologous cyts c, thermophilic Hydrogenobacter thermophilus cytochrome c552 (HT) and mesophilic Pseudomonas aeruginosa cytochrome c551 (PA), exhibit a unique thermodynamic property such that, despite their structural similarity, HT is significantly more stable than PA. Site-directed mutants of PA, for which amino acid substitutions were selected with reference to the corresponding residues in HT, exhibited thermostabilities between those of PA and HT. Furthermore, we found that cyt c with higher stability in its oxidized form exhibits a lower Em value. This finding provides novel insights into the functional regulation of cyts c, which could be utilized for tuning the Em value of the proteins by means of protein engineering.
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  • Thermodynamics at the Region Where Stability Interferes with Dynamics - Thermodynamics of Quantum Cryptography for Representation of Prion -
    Kazuo Kuwata
    2008 Volume 35 Issue 3 Pages 140-147
    Published: June 30, 2008
    Released on J-STAGE: November 20, 2022
    DOIhttps://doi.org/10.11311/jscta.35.3_140
    JOURNAL FREE ACCESS
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     Physical principle that governs the protein's conformational conversion between different conformers, which are far apart in a phase space, remains unknown. Recent development in NMR techniques enabled us to observe the slow dynamics on the time scale of micro- to milliseconds of nuclei in a protein. However, the nature of such a slow motion is generally not well understood. For example, at room temperature the time constant of the refolding of prion protein is about ∼100 mseconds, but that of slow dynamics is between sub-millisecond to milliseconds. During such a slow motion, the native structure has a chance to unfold completely. This kind of slow motion occurs in the critical region where fluctuation interferes with the thermal stability of the conformation.
     In order to describe the protein dynamics in a large phase space, here we have constructed a novel representation theory, termed "the thermodynamics of quantum cryptography", which is essentially based on the number theory. We could represent the conformational rearrangement with an extremely low probability in a critical region. This formalism includes the Dirichlet series to represent the partition function, which consists of periodic trajectories with a prime number step. These theories have been employed to interpret the slow dynamics of prion protein as well as its pathogenicity.
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  • Thermodynamic Properties of Binary Mixtures Containing Several Kinds of Organic Fluorine Compounds
    Takashi Minamihonoki, Hideo Ogawa, Sachio Murakami
    2008 Volume 35 Issue 3 Pages 148-156
    Published: June 30, 2008
    Released on J-STAGE: November 20, 2022
    DOIhttps://doi.org/10.11311/jscta.35.3_148
    JOURNAL FREE ACCESS
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     A number of fluorinated organic compounds has been synthesized and utilized as the alternative solvent to the chlorofluorocarbons. In order to discuss the solvent performance of hydrofluoroether (HFE) and trifluoroethanol (TFE) in aspect of the thermodynamic properties, excess molar enthalpies (HmE) and volumes (VmE) have been determined for binary mixtures containing them at 298.15 K using a home-made twin conduction type of flow microcalorimater equipped with a pair of precision cylinder pumps and Anton-Paar vibrating tube densimeter. The first component liquid of HFE-356mec (CF3CHFCF2OCH3), HFE-347pc-f (CHF2CF2OCH2CF3) and HFE-449 (C4F9OCH3) and TFE, and the second component liquid of several different types of organic solvents were distilled with 1m packed column.
     The HmE and VmE results for the binary mixtures containing HFE were in positive, except for the HmE of HFE ＋ MEK system. HmE value for the TFE ＋ water system showed endothermic mixing, except for the low TFE concentration range. On the other hand, VmE values for this system were negative over the whole range of concentration. HmE values for all the TFE ＋ alcohol systems were exothermic and VmE values of these systems were in positive over the whole range of concentration. Excess partial molar enthalpy (Hm,iE,∞) and volume (Vm,iE,∞) at infinite dilution were also estimated. These results were discussed qualitatively from the viewpoint of the difference in intermolecular interactions between the pure component liquids and the mixtures. HFE and TFE are expected to be a good solvent especially for the polar solvent materials in the cleaning technology of electronic industries.
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