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Volume 67, Issue 12
Displaying 1-8 of 8 articles from this issue
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Comprehensive Papers
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Tsunenori KAMEDA, Katsura KOJIMA, Hideki SEZUTSU, Qiang ZHANG, Hidetos ...Article type: Comprehensive Papers
2010 Volume 67 Issue 12 Pages 641-653
Published: 2010
Released on J-STAGE: December 24, 2010
JOURNAL FREE ACCESSHornet silks, fibrous proteins present in the cocoon produced by the larvae of vespa species, are composed of four major proteins. Complete amino acid sequences of the four major proteins (Vssilk 1-4) in the hornet silk produced by the yellow hornet (Vespa simillima, Vespinae, Vespidae) have been determined. The amino acid sequences in Vssilk 1-4 are highly divergent, but the four proteins have some common properties. The most attractive feature of these proteins is that they have an α-helix region, which includes coiled-coil α-helices, and a β-sheet region. The aforementioned coiled-coil and β-sheet structures are responsible for the intermolecular binding between the Vssilk 1-4 proteins that make up the composite structure in hornet silk. This coiled-coil structure is restored when hornet silk gel films are formed by pressing and drying hornet silk hydrogel. Drawing-induced changes in the orientation and conformation of the coiled-coil structure are investigated in order to clarify the reason for the formation of this structure.
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Atsushi HYONO, Jérôme F. L. DUVAL, Hiroyuki OHSHIMA, Tosh ...Article type: Comprehensive Papers
2010 Volume 67 Issue 12 Pages 654-665
Published: 2010
Released on J-STAGE: December 24, 2010
JOURNAL FREE ACCESSAnalysis of human red blood cells surface properties and evaluation of the interactions among red blood cells were done to establish the mechanism of the enzyme method. Electrophoretic mobilities of intact and enzyme-treated red blood cells were analyzed with soft particle theories; one based on the diffuse models could provide further information about the properties of red blood cell surfaces. Therefore, the interaction energies between two red blood cells were evaluated and the closest distances between them were evaluated to decide the agglutinability of cells with a IgG molecule. It was concluded that thinning of the surface layer thickness plays more important role in the enzyme method than reducing the surface layer charge densities.
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Original Papers
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Fumio HAYASHI, Hidetoshi TOMARU, Kenji OOSAWAArticle type: Original Papers
2010 Volume 67 Issue 12 Pages 666-678
Published: 2010
Released on J-STAGE: December 24, 2010
JOURNAL FREE ACCESSA Salmonella cell swims by rotating its flagellar filaments. Each filament (∼10 μm) is composed of ∼30,000 molecules of a single protein flagellin and forms a left-handed helical structure under physiological conditions. The cells repeat swim-and-tumble and consequently move toward their favored environments and away from unflavored ones. The swim-and-tumble is caused by the change of the filament shape introduced by reversal of flagellar rotation. Such a change of the filament shape is called a polymorphic transformation. To elucidate the transformation mechanism of flagellar filaments, we applied genetic suppressor analysis within flagellin molecule and identified the 19 key amino acid residues contributing to the transformation. To estimate the roles of the key amino acid residues, we analyzed the shapes of the flagellar filaments and the functions (swimming and tumble activities) of the pseudorevertants, and we investigated the localization of the key amino acid residues on L- and R-type flagellin molecules. From these results, we propose a novel mechanism for the polymorphic transformation.
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Tomoyuki KOGA, Chie NISHIUMA, Nobuyuki HIGASHIArticle type: Original Papers
2010 Volume 67 Issue 12 Pages 679-685
Published: 2010
Released on J-STAGE: December 24, 2010
JOURNAL FREE ACCESSIn this work, poly(ethylene glycol)-modified elastin-like peptides, (VPGVG)4-PEG and (GVGPV)4-PEG, were newly designed and synthesized to fabricate thermo-responsive polymer materials. Temperature-dependent structural and self-assembling properties of these block-type peptide-polymer hybrids in water were examined by using CD, DLS and AFM measurements. CD spectra showed that the conformations of both ELP segments changed from random coil to ordered structure involving type II β-turns along with the temperature rise, suggesting that PEG segments attached to the C-terminus of the peptides did not influence the conformational property of ELP segments. DLS and AFM measurements showed that both diblock polymers formed spherical micelle-like aggregates in response to such conformational switches of ELP segment, although the diameters of the aggregates strongly depended on the amino acid sequence. Hydrophilic PEG segments seem to stabilize such assembled structures by covering hydrophobic β-turned ELP core in water.
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Yusuke KITA, Ken TERAO, Takahiro SATOArticle type: Original Papers
2010 Volume 67 Issue 12 Pages 686-689
Published: 2010
Released on J-STAGE: December 24, 2010
JOURNAL FREE ACCESSA collagen model peptide (Pro-Pro-Gly)5(PPG5) was complexed with polyacrylic acid (PAA) in methanol including 10 mM LiClO4. While PPG5 solutions of a concentration 3.23×10−5 g cm−3 were turbid at the molar ratios of PAA to PPG5 Cp/Cc=0.06 and 0.3, the solution was transparent at Cp/Cc=3. Circular dichroism measurements on PPG5 solutions showed that the addition of PAA up to Cp/Cc=3 increases the triple helix-coil transition temperature by ca. 30 K, indicating that the triple helical structure is significantly stabilized in the presence of small amounts of PAA. An association-dissociation equilibrium between PPG5 and PAA was proposed to explain the stabilization of the PPG5 triple helix by PAA.
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Keiichi NOGUCHI, Masakazu KANENARI, Kenji OKUYAMA, Kozo OGAWAArticle type: Original Papers
2010 Volume 67 Issue 12 Pages 690-697
Published: 2010
Released on J-STAGE: December 24, 2010
JOURNAL FREE ACCESSThe crystal structure of chitosan/hydrogen bromide (HBr) complex was analyzed using synchrotron X-ray fiber diffraction data. The crystals belong to the monoclinic space group P21. The unit cell constants are a=9.299(9), b=9.504(8), c(fiber axis)=10.41(1) Å and β=106.93(8)°. The final model was obtained by the linked-atom least-squares refinement, which gave an R-factor of 0.191 (93 observed spots). The unit cell contains two polymer chains (four glucosamine residues) and four HBr molecules. The chitosan chain adopts 2/1-helical conformation. The orientation of O6 oxygen is nearly gt; it plays a role as proton donor to bromide ions and as proton acceptor from NH3+ groups (N2 nitrogen) of adjacent chitosan chains. The bromide ions are aligned along the c-axis at intervals of about 5 Å and are surrounded by four polymer chains. Two types of bromide ions exist in an asymmetric unit. One bromide ion participates in three hydrogen bonds from N2, and the other one participates in one hydrogen bond from N2 and two hydrogen bonds from O6.
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Tetsuya ABE, Shinpei ITO, Naoya NISHI, Yoshihiro TSUKADA, Takuo YASUNA ...Article type: Original Papers
2010 Volume 67 Issue 12 Pages 698-704
Published: 2010
Released on J-STAGE: December 24, 2010
JOURNAL FREE ACCESSIn this study, we expressed, purified and characterized small heat shock proteins (sHsp) from a magnetotactic bacterium, Magnetospirillum magneticum AMB-1, Hsp17.5, Hsp17.8 and Hsp18.3. They all showed molecular chaperone activity to protect citrate synthase from thermal aggregation at 45°C. The oligomeric states were examined by size exclusion chromatography and electron microscopy. Hsp17.8 exists as a spherical oligomer like other sHsps, and the oligomer reversibly dissociates to small conformers, probably dimers, at elevated temperatures. On the contrary, Hsp17.5 and Hsp18.3 take large filamentous conformations. A similar structure was observed in an sHsp of Sulfolobus tokodaii, StHsp19.7, but it did not exhibit molecular chaperone activity. Hsp17.5 and Hsp18.3 changed their oligomeric states according to the elevation of temperature. Among them, Hsp17.5 exhibited reversible dissociation. This is the first report that the filamentous sHsp exhibit molecular chaperone activity with the change of oligomeric states.
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Notes
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Tada-Aki YAMAGISHI, Akihiko ISHIZAKI, Tomoki OGOSHI, Yoshiaki NAKAMOTO ...Article type: Notes
2010 Volume 67 Issue 12 Pages 705-708
Published: 2010
Released on J-STAGE: December 24, 2010
JOURNAL FREE ACCESSWe have designed a new material with stable cholesteric structure by blending a cellulose derivative, (acetoxypropyl)cellulose (APC), with a thermoplastic polymer, poly(viny acetate) (PVAc). In the material obtained from THF solution, the compatibility between APC and PVAc was confirmed by differential scanning calorimetry (DSC) and infrared spectroscopy (IR). The materials showed colors arising from the selective reflection of circular polarized light. The colors depended on the composition of the materials. The material obtained from acetone solution showed phase separation into an APC rich phase and a PVAc rich phase, respectively. This indicated that the aggregation structure of APC/PVAc blends was affected by the preparation condition for materials. The FT IR results supported that the molecular aggregation structure was controlled by the hydrogen bonds between APC and PVAc polymer chains.
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