Netsu Sokutei

[title in Japanese]

[in Japanese], [in Japanese], [in Japanese], [in Japanese], [in Japane ...

2007 Volume 34 Issue 1 Pages 2
Published: January 25, 2007
Released on J-STAGE: September 07, 2009

DOIhttps://doi.org/10.11311/jscta1974.34.2

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What Some Anions do to H₂O?

Towards Understanding the Hofmeister Series

Yoshikata Koga

2007 Volume 34 Issue 1 Pages 3-13
Published: January 25, 2007
Released on J-STAGE: September 07, 2009

DOIhttps://doi.org/10.11311/jscta1974.34.3

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The effects of selected anions on the molecular organization of H₂O are elucidated by the 1-propanol (1P) probing methodology developed by us. We determine the third derivative quantity, the 1P-1P enthalpic interaction, H^E_1P-1P, in ternary system of 1P-sample salt (S)-H₂O. In the presence of S, the H^E_1P-1P pattern changes while keeping the basic peak anomaly. These induced changes are used to elucidate the effect of S on H₂O. We found within the sodium salts of SO₄^2-, F^-, Cl^-, Br^-, I^- and ClO₄^- that the first three act basically as hydration centers. The hydration numbers are 17, 14 and 2.3, respectively. The remaining Br^-, I^- and ClO₄^- are basically hydrophiles. They form hydrogen bonds directly to the existing hydrogen bond network of H₂O and thus work as impurity centers in the existing network, retarding the degree of fluctuation inherent in H₂O. Their effects are stronger in the order of Br^- < I^- < ClO₄^-. Thus in terms of the Hofmeister effects, the kosmotropes (salting out agents) are hydration centers and the more the hydration number, the stronger the salting out effect. The chaotropes (salting in reagents), Br^-, I^- and ClO₄^-, are hydrophiles, and the stronger the hydrophilicity the stronger the salting-in power.

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Some Remarks after Construction of the Thermodynamic Database MALT

Harumi Yokokawa, Shigeru Yamauchi, Takafumi Matsumoto

2007 Volume 34 Issue 1 Pages 14-21
Published: January 25, 2007
Released on J-STAGE: September 07, 2009

DOIhttps://doi.org/10.11311/jscta1974.34.14

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On the basis of the development of the thermodynamic database MALT, several issues related with the thermodynamic database and related systems which utilize thermodynamic data stored in database have been discussed. Focuses were placed on evaluation methods of loosely connected thermochemical data and its combination with well generalized software to calculate chemical equilibria or to construct the generalized chemical potential diagrams. Particular emphases were placed on appropriateness of applying the generalized software together with a set of data where some critical data are missing. Considerations were made on how thermodynamic database should be combined with such knowhows of utilizing thermodynamic data far from the complete coverage of data.

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Thermodynamic Studies of Functional Perovskite-Related Oxides

Tôru Kyômen

2007 Volume 34 Issue 1 Pages 22-30
Published: January 25, 2007
Released on J-STAGE: September 07, 2009

DOIhttps://doi.org/10.11311/jscta1974.34.22

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Thermodynamic studies of spin-state transition and magnetoresistance effects in perovskite-type oxides are introduced. The temperature dependences of magnetic susceptibility and heat capacity due to spin-state transition of LaCoO₃ are well reproduced by introducing a free energy of mixing of low-spin Co ions in the ground state and high-spin Co ions in the excited state. The present results indicate that the energy of mixing is negative, which suggests that repulsive interaction acts between high-spin Co ions. In addition, it was found in metallic ferromagnets La_0.6Sr_0.4CoO₃, SrRuO₃, and CoPt₃ that the magnetoresistance is proportional to the entropy suppression by applying magnetic fields. This proportional relation was observed above, at, and just below their Curie temperatures.

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Thermodynamic Analysis of Conformational Change Important to Protein Function

Masayuki Oda

2007 Volume 34 Issue 1 Pages 31-36
Published: January 25, 2007
Released on J-STAGE: September 07, 2009

DOIhttps://doi.org/10.11311/jscta1974.34.31

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In the present post-genome era, although many three-dimensional structures of proteins have been determined at atomic resolution mainly by X-ray structural analysis, there remain some problems, such as dynamic properties of proteins and hydration effects, to clarify the correlation between protein structure and function. Proteins are flexible and need some conformational changes to recognize other molecules, but it is difficult to detect the dynamic properties only by static structural analyses. Thermodynamic analyses of biomolecular interactions reveal details of the energetic and dynamic features of molecular recognition processes, and complement the structural information. I have investigated several biomolecular interactions, including DNA-protein, antigen-antibody, and peptide-protein interactions, using isothermal titration and differential scanning calorimetries, together with other methods, such as NMR, X-ray, and surface plasmon resonance. Here, I focus on the thermodynamics to detect conformational changes of proteins, which is important for biomolecular function in general.

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[title in Japanese]

2007 Volume 34 Issue 1 Pages 37-39
Published: January 25, 2007
Released on J-STAGE: September 07, 2009

DOIhttps://doi.org/10.11311/jscta1974.34.37

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