納豆粘質物成分ポリ-γ-グルタミン酸の新規な機能性 : 2価鉄に起因する細胞障害の防御

ポリ-γ-グルタミン酸(PGA)の2価鉄(Fe²⁺)による細胞障害に対する抑制効果を，大腸菌の生存率を計測することで検討した。LB液体培地，蒸留水および生理食塩水で希釈した菌体を用いて，Fe²⁺殺菌効果を検討したところ，蒸留水で希釈した大腸菌は10⁻⁶MのFe²⁺で生育阻害がみられたが，LB培地と生理食塩水で希釈した場合は，10⁻³Mで殺菌効果が認められた。蒸留水を用いた場合，Fe²⁺が菌体表面に付着する影響が考えられたので生理食塩水を希釈溶液として用いた。Fe²⁺の殺菌作用に対するキレート試薬の影響を検討した。EDTA，DTPAともに，加えたFe²⁺と当モルの濃度でほぼ完全に殺菌作用を阻害した。このキレート試薬の効果はFe²⁺の自動酸化を促進させることによりFe²⁺の実効濃度が低下したためと考えられた。Fe²⁺の殺菌作用に対するPGAの影響を調べた結果，保護効果が認められた。PGA の鎖長に関係なく，生存率が約30％から約70％へ増加した。単量体のグルタミン酸は生存率に影響しなかった。以上の結果より，PGAはFe²⁺による殺菌作用を抑制することが示された。このことはPGAが鉄毒を抑制する機能を有していることを示唆している。The protective effect of poly-γ-glutamic acid （PGA） against oxidative damage derived from ferrous iron （Fe²⁺） was investigated using a viability test of　Escherichia coli. To establish the conditions for the viability test, the Fe²⁺ concentration which gives rise to cell death was determined. The critical concentration of Fe²⁺ depended upon the solution in which the cells were suspended. In an LB medium, a mM level of Fe²⁺ was required to bring about cell death, whereas in distilled water a μM level was required. In saline solution, a bactericidal effect was observed at a concentration in the order of mM. Thus, saline solution was employed as the cell dilution solution.EDTA treatment completely prevented Fe²⁺-derived cell death, with an equimolar concentration of each chelator and Fe²⁺ of 0.5 mM. DTPA treatment showed a similar effect. The protective effect of the chelators was attributable to the non-availability of Fe²⁺, which was eliminated through accelerated autoxidation with the chelators.PGA protected the cells from the bactericidal action of Fe²⁺. When PGA was added to form a 1:1 complex with Fe²⁺, cell viability was restored from 30% to 70%. Treatment with glutamic acid showed no effect. These results indicate that PGA has a novel function of protecting cells from Fe²⁺ toxicity

Immunolocalization of antioxidant enzymes in high-pressure frozen root and stem nodules of Sesbania rostrata

34 Pags.- 7 Figs.- 1 Tabl. The definitive version is available at: http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1469-8137The activities and localizations of superoxide dismutases (SODs) were compared in root and stem nodules of the semi-aquatic legume Sesbania rostrata using gel-activity assays and immunogold labelling, respectively. Nodules were fixed by high-pressure freezing and dehydrated by freeze substitution. Stem nodules showed more total and specific SOD activities than root nodules because of the presence of chloroplastic CuZnSOD. Most of the total SOD activity of stem and root nodules resulted from 'cytosolic' CuZnSOD, localized in the cytoplasm and chromatin, and from MnSOD in the bacteroids and in the mitochondria of vascular tissue. FeSOD was present in nodule plastids and in leaf chloroplasts, and was found to be associated with chromatin. Superoxide production was detected histochemically in the vascular bundles and in the infected tissue of stem and root nodules, whereas peroxide accumulation was observed in the cortical cell walls and intercellular spaces, as well as within the infection threads of both nodule types. These data suggest a role of CuZnSOD and FeSOD in protecting nuclear DNA from reactive oxygen species and/or in modulating gene activity. The enhanced levels of CuZnSOD, MnSOD and superoxide production in vascular bundle cells are consistent with a role of CuZnSOD and superoxide in the lignification of xylem vessels, but also suggest additional functions in coping with superoxide production by the high respiratory activity of parenchyma cells.This work was supported by the Royal Society (UK), Ministerio de Educación y Ciencia-Fondos Europeos de Desarrollo Regional (AGL2005-01404 and AGL2008-01298) and Gobierno de Aragón (group A53). E.K.J. thanks the Royal Society (UK) and Gobierno de Aragón-Caja Inmaculada (Spain) for funding a sabbatical leave (‘Programa Europa’). M.C.R. was the recipient of a postdoctoral contract (Program I3P) of Consejo Superior de Investigaciones Científicas-Fondo Social Europeo.Peer Reviewe

もち大麦粉を使用したパウンドケーキの特性と嗜好性

We prepared samples of pound cake by substituting soft wheat flour with waxy barley flour, a rich source of water-soluble dietary fiber, at levels of 0（control）, 25, 50, 75, and 100% to examine their physical and sensory characteristics. As the results, no marked difference was found among these samples in terms of weight and height, but the volume of the samples increased by 1.2-fold at 100% substitution. The sensory evaluation showed that the higher the substitution level, the lower the ratings. Because of the distinctive aroma and flavor of waxy barley flour, the test samples failed to receive sensory ratings comparable with those of the control sample, although participants reported the waxy-barley pound cake as tasty when asked in an openresponse format. In conclusion, pound cake prepared with waxy barley flour is likely to receive lower ratings for sensory attributes than cake made with 100% soft wheat flour, due to its distinctive aroma and flavor; however, considering its palatability, unique texture, and dietary fiber content, waxy-barley pound cake can be enjoyed as a tasty snack that could be beneficial for the prevention of lifestyle-related diseases. Further investigation is needed to improve the sensory quality of waxy-barley pound cake

光励起リボフラビンによるアスコルビン酸からのH₂O₂の生成機構

光励起リボフラビン(Rib)存在下でのアスコルビン酸(Asc)の光酸化におけるH₂O₂生成機構について,Asc,H₂O₂,O₂間の化学量論関係をもちいて検討した。1.25 μM または12.5 μM Rib の存在下,Ascの光酸化によるO₂吸収速度は光強度に比例した。O₂吸収量に対するH₂O₂生成量のモル比は,光強度の増大とともに増加し,高光強度で約0.5の一定値になった。ローズベンガル(RB)を光増感剤とした場合は,0.125 μM Rb 存在下では,H₂O₂/O₂比は光強度に依存せず約0.5であった。1.25 μM RBでは,Rib の場合と同様の傾向を示し,比は最終的に約0.6であった。Asc光酸化におけるO₂⁻が関与するType Iおよび¹O₂ が関与するType II反応の寄与の割合を検討するために,SOD や¹O₂ 消光剤の影響を調べた結果,Type II反応と伴にType I反応も関与していることが示された。空気開放系でAscを完全に酸化させた場合,Ascと生じたH₂O₂ の化学量論関係は1: 2であった。以上の結果から得られたH₂O₂/O₂比とH₂O₂/Asc比を満足させる反応機構を考察した。An H₂O₂ generation pathway for ascorbic acid (Asc) oxidation in the presence of sensitized riboflavin (Rib) was investigated by analyzing the stoichiometric relation between H₂O₂, Asc　and O₂. When 1.25 or 12.5 μM Rib was present, the O₂ uptake rate of Asc photooxidation　increased linearly with increasing light intensity. The molar ratio of the amount of O₂ uptake to the amount of H₂O₂ produced increased with increasing light intensity, and then became a constant value of approx. 0.5. With 0.125 μM rose bengal (RB) instead of Rib, the ratio of H₂O₂/ O₂ did not depend on light intensity, and was about 0.5. When 1.25 μM RB was used, the ratio showed similar patterns to those of Rib, and a constant value of approx. 0.6 was obtained.To determine the contribution of Type I and Type II reactions in Asc photooxidation, the effect of SOD and ¹O₂ quencher on the O₂ uptake rate was investigated. The results showed the occurrence of not only Type II but also Type I reactions. When Asc was oxidized completely in open air, the stoichiometry of Asc to H₂O₂ was 1:2. Based on these results, we discussed a pathway of Asc photooxidation to accommodate the obtained values of H₂O₂/O₂ and H₂O₂/Asc

Cu, Zn[-], Mn[-]およびFe[-]スーパーオキシドジスムターゼに関する生物系統進化学的, 生化学的研究

京都大学0048新制・論文博士農学博士乙第6148号論農博第1300号新制||農||456(附属図書館)学位論文||S62||N1777(農学部図書室)UT51-62-C141(主査)教授 淺田 浩二, 教授 森田 雄平, 教授 千田 貢学位規則第5条第2項該当Kyoto UniversityDFA