Akira Makabe

Akita University, Akita, Akita-ken, Japan

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Publications (4)4.04 Total impact

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    ABSTRACT: Regioselectively hetero-labeled hosts, 6A-pyrenebutylate-6X-tosyl-modified gamma-cyclodextrins (X = B or H, C or G, D or F, and E for gamma-1, gamma-2, gamma-3, and gamma-4, respectively), were synthesized in order to investigate their chemo-sensor properties for applications to organic compounds, such as bile acids and terpenes. The hosts (gamma-1, gamma-2, gamma-3, and gamma-4) exhibit pure monomer fluorescence. The guest-induced fluorescence emissions of these hosts were suppressed in the presence of guests. The extent of fluorescence variations of these hosts with guests was recognized as a manifestation of the sensing ability of the hosts. A sensing parameter (deltaI/I0, where I and I0 are the fluorescence intensities in the presence and absence of a guest and deltaI = I0-I) was used to describe the sensing ability of these hosts. Host gamma-analogs were able to detect progesterone, ursodeoxycholic acid, chenodeoxycholic acid, and (-)-borneol with high sensitivity. The behaviors of the appended moieties of these hosts during the formation of host-guest complexes were studied using induced circular dichroism (ICD) spectra, fluorescence spectra and the MM2-energy-minimized structure. The host gamma-analogs exhibited different ICD spectra patterns before and after the addition of ursodeoxycholic acid. The guest-induced variations of ICD and the fluorescence spectra and MM2-minimized structures suggest that the pyrene and tosyl moieties move by altering the spatial relationship between them, in which the pyrene moiety works as a hydrophobic cap and the tosyl moiety is speculated to act as a spacer.
    Analytical Sciences 03/2002; 18(2):119-24. · 1.57 Impact Factor
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    ABSTRACT: The effect of dansyl modified -cyclodextrin (1)on the chaperone activity of heat shock proteins such as HSP70 and HSP90 hasbeen studied. The fluorescence intensity of 1 was decreased when HSP70 and HSP90 were added to the host solution. This phenomenon suggested that host–guest complexation was occuring. The binding constants of 1 were obtained using a 1:1 complex formation type equation by employing the guest-induced fluorescence variations. Host 1 exhibited a higher binding ability forHSP70 than for HSP90. The effects of 1 on the chaperone activity and degradation of HSP70 and HSP90 were studied by measuring the absorption of aggregation of citrate synthase (C.S.) and sodium dodecyl sulfate (SDS)polyacrylamide gel electrophoresis of trypsin degradation, respectively. Host1 can contribute to regulate C.S. aggregation andpromote trypsin degradation of HSP70 and HSP90.
    Journal of Inclusion Phenomena 05/2001; 40(1):83-88. · 1.40 Impact Factor
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    ABSTRACT: Flexible regioselectively hetero-substituted hosts, 6A-O-4-pyrenylbutanoyl-6X-O-p-cyanobenzoyl-modified γ-cyclodextrins (X = B or H, C or G, D or F, and E for γ-1, γ-2, γ-3, and γ-4, respectively) have been synthesized in order to investigate their fluorescence sensing properties for application to organic compounds such as bile acids and cyclic alcohols. The hosts, γ-1, γ-2 and γ-3, exhibit both monomer and exciplex fluorescence, whereas γ-4 exhibits only monomer emission. In guest-induced emission of γ-1, γ-2 and γ-3, exciplex emission is suppressed while monomer emission is increased. However, γ-4 exhibits only a negligible change in monomer fluorescence in the presence of guests. The extent of exciplex fluorescence variation of γ-1, γ-2 and γ-3 with guests is recognized as the manifestation of the sensing ability of the hosts. A sensing parameter (ΔIex/I0ex) was used to describe the sensing ability of three hosts. Host γ-analogs, γ-1, γ-2 and γ-3, are able to detect ursodeoxycholic acid, deoxycholic acid, chenodeoxycholic acid, and (−)-borneol with high sensitivity by exciplex emission. The sequence of the binding ability of these hosts is γ-2 > γ-1 > γ-3. The behaviors of the appended moieties of these hosts during the formation of host–guest complexes were studied using induced circular dichroism (ICD) and fluorescence spectra. The host γ-analogs γ-1–γ-3 exhibit different ICD patterns to γ-4 before and after addition of ursodeoxycholic acid. The guest-induced variations of ICD and fluorescence spectra changes suggest that the pyrene and cyanobenzene moieties move, altering the spatial relationship between them.
    Journal of the Chemical Society Perkin Transactions 2 01/2001;
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    ABSTRACT: The discharge property in the solid state has been utilized for ceramics processing and printer technology. The charge of particles has to be controlled in these fields because it affects the particle filling process in ceramics processing and the print quality of a printer. Fine silica particles are used to refine ceramics or resin particles for optimization of flowability, the discharge ability and the wettability. However, it is difficult to understand these properties, because critical factors ``affecting'' for these properties have not been elucidated yet. For example, the discharge property has not been examined in connection with the surface chemical structure of particles. In this study, we report the electron accepting or electron donating ability of chemicals and find that the discharge property is significantly influenced by that ability. Work function values are measured for polystyrene resin particles covered by different kinds of silica particles. In addition, we suggest a simple evaluation method for solid discharge through the measuring of pH in solution form. The relationships among the discharge, pH and work function values are examined. As a result, we arrive at some results to elucidate these phenomena.
    Japanese Journal of Applied Physics 01/2001; 40:7117-7122. · 1.07 Impact Factor