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Volume 28 (2001)
- Issue 5 Pages 200-
- Issue 4 Pages 164-
- Issue 3 Pages 106-
- Issue 2 Pages 54-
- Issue 1 Pages 2-
Volume 28, Issue 2
Displaying 1-10 of 10 articles from this issue
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Kunimasa Koga, Shin-ichi Hiraoka, Yeong Su Kim, Daisuke Hagiwara, Yasu ...2001 Volume 28 Issue 2 Pages 54-61
Published: March 31, 2001
Released on J-STAGE: September 07, 2009
JOURNAL FREE ACCESSUsing calorimetric method, heat evolutions associated with the growth of soil microbes (growth thermograms) during microbial decomposition of added organic matters (yeast extracts) in various kinds of soils were studied. Soils tested were soils from vegetable garden, from mountain area, from a playground, from tea garden and sea sands from beach. From the actual heat evolution curves (f(t) curves) derived from the growth thermograms, the “apparent growth rate constant (μ′)” of soil microbes was determined. As the μ′ value of soil microbes can be regarded as a decomposition rate constant (kd) of yeast extracts added, the abilities of decomposing the yeast extracts were compared for each of the soils.
From the results, the followings were obtained: (1) The calorimetry of solid microbes is a usable technique to quantitatively estimate the ability of organic matter decomposition in soils. (2) The ability of organic matter decomposition is considerably different depending on the kind of soils. (3) The decomposition ability of sea sand solids from beach is much higher than those of the other soils. (4) The decomposition ability of tea garden soil is considerably lower than that of the others.
On the basis of the above results, we conclude that the method employed in this study provides more quantitative information about the ecological potential than any other existing methods and that the present calorimetric method contributes to the land improvement in terms of the material cycling as well as the agricultural production.View full abstractDownload PDF (1755K) -
Y. Kimura, H. Fukada, M. Kodama2001 Volume 28 Issue 2 Pages 62
Published: March 31, 2001
Released on J-STAGE: September 07, 2009
JOURNAL FREE ACCESSDownload PDF (129K) -
Ingemar Wadsö2001 Volume 28 Issue 2 Pages 63-67
Published: March 31, 2001
Released on J-STAGE: September 07, 2009
JOURNAL FREE ACCESSThe importance of uniform terminology and standardised chemical calibration and test processes for titration microcalorimetry are discussed. Calorimeters are normally calibrated electrically, but in the case of microcalorimeters, results from such calibration experiments can easily lead to significant systematic errors. The quality of results will often improve if a chemical calibration technique is used. In order to test the properties of a calorimeter and to validate the results, it is important to have available suitable test reactions. References are given to some standardised chemical calibration and test processes for titration microcalorimetry.View full abstractDownload PDF (1294K) -
Adrian Velazquez-Campoy, Irene Luque, Ernesto Freire2001 Volume 28 Issue 2 Pages 68-73
Published: March 31, 2001
Released on J-STAGE: September 07, 2009
JOURNAL FREE ACCESSIsothermal Titration Calorimetry (ITC) plays a central role in the characterization and optimization of lead compounds as viable drug candidates. ITC is the only technique that permits a complete experimental characterization of the binding affinity of a ligand in terms of its thermodynamic components ΔG, ΔH, ΔS and ΔCp. In addition, ITC is ideally suited to characterize coupled processes like protonation/deprotonation reactions. One of the major challenges for ITC has been the analysis of ligands with high binding affinities. This issue becomes a serious problem in drug design, where one of the main goals is to optimize the binding affinities of lead compounds to nanomolar or subnanomolar levels. These binding affinities have been traditionally considered to be beyond the useful range of calorimetric analysis. In this paper we will discuss the implementation of ITC experimental designs aimed at characterizing very high affinity binding processes (Ka > 109M-1) and apply them to the characterization of HIV-1 protease inhibitors. We will also discuss the characterization of protonation/deprotonation coupling to the binding reaction.View full abstractDownload PDF (1275K) -
Shun-ichi Kidokoro2001 Volume 28 Issue 2 Pages 74-82
Published: March 31, 2001
Released on J-STAGE: September 07, 2009
JOURNAL FREE ACCESSQuantitative evaluation of catalytic activity of enzymes against various substrates under several solution conditions is important to understand the catalytic mechanism. In this paper, the titration calorimetry was applied to evaluate the catalytic activity of a protease not only in the condition of peptide digestion but also in that of peptide synthesis. Two calorimetric observables, the compensation power and its integrals can be determined directly and precisely by titration calorimetry. In the hydrolytic condition, a calorimetric Lineweaver-Burk plot and non-linear least-squares method with these two observables were found to be effective to determine the enzymatic parameters precisely. Moreover, the enthalpy change accompanying the catalytic reaction can be determined with no information on the enzyme concentration and initial substrate concentration by this method with comparing the results of spectroscopic method. In the synthetic condition where the spectroscopic method can not be applied practically, the catalytic activity of the enzyme was shown to be determined quantitatively by titration calorimetry. The feature of direct observation of the reaction rate by calorimetry is considered to give us an effective and precise way to evaluate the protease activity.View full abstractDownload PDF (1518K) -
Hidetaka Torigoe2001 Volume 28 Issue 2 Pages 83-90
Published: March 31, 2001
Released on J-STAGE: September 07, 2009
JOURNAL FREE ACCESSTo understand the mechanism of affinity maturation, the antigen-antibody interactions between 4-hydroxy-3-nitrophenylacetyl caproic acid (NP-Cap) and the Fab fragments of three anti-4-hydroxy-3-nitrophenylacetyl (NP) antibodies, N1G9, 3B44, and 3B62, were examined by isothermal titration calorimetry. The analyses revealed that all of these interactions were mainly driven by negative changes in enthalpy. The enthalpy changes decreased linearly with temperature in the range of 25∼45°C, producing negative changes in heat capacity. On the basis of the dependency of binding constants on the sodium chloride concentration, it was shown that, during the affinity maturation of the anti-NP antibody, the electrostatic effect did not significantly contribute to the increase in the binding affinity. It was also found that, as the logarithm of the binding constants increased during the affinity maturation of the anti-NP antibody, the magnitudes of the corresponding enthalpy, heat capacity, and unitary entropy changes increased almost linearly. On the basis of this correlation, it is concluded that, during the affinity maturation of the anti-NP antibody, a better surface complementarity is attained in the specific complex to obtain a higher binding affinity.View full abstractDownload PDF (1585K) -
Katsuhide Yutani, Kyoko Ogasahara2001 Volume 28 Issue 2 Pages 91-97
Published: March 31, 2001
Released on J-STAGE: September 07, 2009
JOURNAL FREE ACCESSA characteristic property of the tryptophan synthase α2β2 complex is the mutual activation of the α and β subunit upon complex formation. It has been speculated that this mutual activation results from the conformational change due to the α/β subunit interaction. In order to elucidate this mechanism, the association for the various combinations of the α and β subunits from mesophiles, Escherichia coli and Salmonella typhimurium, and for the two subunits from a hyperthermophile, Pyrococus furiosus, was examined using isothermal titration calorimetry. In mesophile proteins, the analyses of the thermodynamic parameters of association indicate that both the α and β subunits fold coupled with the association and the folding might occur not only at the subunit contact surface but also at the other parts in the molecules. This conformational rearrangement might be the origin of mutual activation. The thermodynamic measurements also revealed that the substitution of only one residue in the subunit interface of the E. coli α subunit changed the thermodynamic properties of association with the β subunit similar to those of the S. typhimurium α subunit. On the other hand, the association between α and β2 subunit from P. furiosus was characterized by substantially low values of association enthalpy and association heat capacity changes. This suggests that the folding coupled with the association decreases at low temperatures around 40°C examined. This relates with remarkably low activities around 40°C, as compared with those of mesophile proteins. These differences in thermodynamic properties were discussed on the basis of X-ray structures of both proteins.View full abstractDownload PDF (1114K) -
2001 Volume 28 Issue 2 Pages 98
Published: March 31, 2001
Released on J-STAGE: September 07, 2009
JOURNAL FREE ACCESSDownload PDF (196K) -
Yoshitaka Ishimuro, Hideaki Takahashi2001 Volume 28 Issue 2 Pages 99-100
Published: March 31, 2001
Released on J-STAGE: September 07, 2009
JOURNAL FREE ACCESSDownload PDF (304K) -
2001 Volume 28 Issue 2 Pages 104
Published: 2001
Released on J-STAGE: September 07, 2009
JOURNAL FREE ACCESSDownload PDF (128K)
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