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論文

Cross-scale analysis of temperature compensation in the cyanobacterial circadian clock system

古池 美彦*; Ouyang, D.*; 富永 大輝*; 松尾 龍人*; 向山 厚*; 川北 至信; 藤原 悟*; 秋山 修志*

Communications Physics (Internet), 5(1), p.75_1 - 75_12, 2022/04

 被引用回数:0 パーセンタイル:0.01(Physics, Multidisciplinary)

Circadian clock proteins often reveal temperature-compensatory responses that counteract temperature influences to keep their enzymatic activities constant over a physiological range of temperature. This temperature-compensating ability at the reaction level is likely crucial for circadian clock systems, to which the clock proteins are incorporated, to achieve the system-level temperature compensation of the oscillation frequency. Nevertheless, temperature compensation is yet a puzzling phenomenon, since side chains that make up the clock proteins fluctuate more frequently due to greater thermal energy at higher temperature. Here, we investigated temperature influences on the dynamics of KaiC, a temperature-compensated enzyme (ATPase) that hydrolyzes ATP into ADP in the cyanobacterial circadian clock system, using quasielastic neutron scattering. The frequency of picosecond to subnanosecond incoherent local motions in KaiC was accelerated by a factor of only 1.2 by increasing the temperature by 10$$^{circ}$$C. This temperature insensitivity of the local motions was not necessarily unique to KaiC, but confirmed also for a series of temperature-sensitive mutants of KaiC and proteins other than clock-related proteins. Rather, the dynamics associated with the temperature-compensatory nature of the reaction- and system-level was found in global diffusional motions, which was suggested to regulate the temperature dependence of ATPase activity and dephosphorylation process presumably through changes in the hexamer conformation of KaiC. The spatiotemporal scale at which cross-scale causality of the temperature sensitivity is established is finite, and extends down to picosecond to subnanosecond dynamics only in a very limited part of KaiC, not in its entire part.

論文

Segmental motions of proteins under non-native states evaluated using quasielastic neutron scattering

藤原 悟*; 松尾 龍人*; 杉本 泰伸*; 柴田 薫

Journal of Physical Chemistry Letters (Internet), 10(23), p.7505 - 7509, 2019/12

 被引用回数:2 パーセンタイル:7.04(Chemistry, Physical)

無秩序なポリペプチド鎖のダイナミクスの特性評価は、本質的に無秩序状態なタンパク質およびフォールディングプロセスに関連する非ネイティブ状態下のタンパク質の挙動を解明するために必要である。本研究では、小角X線散乱測定データと動的光散乱測定データと組み合わせて準弾性中性子散乱測定データから、タンパク質のセグメント運動と分子全体の拡散および局所側鎖運動を評価する方法を独自に開発した。そしてこの方法を、非フォールディング状態およびメルトグロビュール(MG)状態のタンパク質RNase Aに適用し、セグメント運動から生じる拡散係数を評価し、非フォールディング状態とMG状態で異なる値をとることを明らかにした。またこの方法で得られた値は、蛍光現象を用いた別の測定技術を使用して得られた値と一致していることも確認できた。これらの研究成果は、この方法の、さまざまな無秩序状態でのタンパク質の挙動を特徴付ける実行可能性だけでなく、有用性も示している。

論文

Dynamic properties of human $$alpha$$-synuclein related to propensity to amyloid fibril formation

藤原 悟*; 河野 史明*; 松尾 龍人*; 杉本 泰伸*; 松本 友治*; 成田 哲博*; 柴田 薫

Journal of Molecular Biology, 431(17), p.3229 - 3245, 2019/08

 被引用回数:6 パーセンタイル:27.55(Biochemistry & Molecular Biology)

パーキンソン病発症には、脳細胞中の「$$alpha$$-シヌクレイン」というタンパク質が線維状に集合した状態(「アミロイド線維」と呼ばれる)となることが関係すると考えられており、どのようなメカニズムでこのアミロイド線維が形成されるのかに強い関心が寄せられている。そこで研究チームは、タンパク質分子の「動き」に着目し、アミロイド線維のできやすさが様々に異なった条件でのタンパク質の動きを、J-PARCの中性子準弾性散乱装置を用いて調べた。その結果、タンパク質分子の動きの違いによりアミロイド線維のできやすさが変わること、特にアミロイド線維ができるためには、タンパク質同士が集合しやすくなるような特定の動きが必要なことを明らかにした。

論文

Difference in the hydration water mobility around F-actin and myosin subfragment-1 studied by quasielastic neutron scattering

松尾 龍人; 荒田 敏昭*; 小田 俊郎*; 中島 健次; 河村 聖子; 菊地 龍弥; 藤原 悟

Biochemistry and Biophysics Reports (Internet), 6, p.220 - 225, 2016/07

Hydration water is essential for a protein to perform its biological function properly. In this study, the dynamics of hydration water around F-actin and myosin subfragment-1 (S1), which are the partner proteins playing a major role in various cellular functions related to cell motility, was characterized by incoherent quasielastic neutron scattering (QENS). The QENS spectra of hydration water around F-actin and S1 provided the translational diffusion coefficient, the residence time, and the rotational correlation time. The differences in these parameters indicate a significant difference in mobility of the hydration water between S1 and F-actin: S1 has the typical hydration water, the mobility of which is reduced compared with that of bulk water, while F-actin has the unique hydration water, the mobility of which is close to that of bulk water rather than the typical hydration water around proteins.

論文

Dynamical behavior of human $$alpha$$-synuclein studied by quasielastic neutron scattering

藤原 悟; 荒木 克哉*; 松尾 龍人; 八木 寿梓*; 山田 武*; 柴田 薫; 望月 秀樹*

PLOS ONE (Internet), 11(4), p.e0151447_1 - e0151447_17, 2016/04

 被引用回数:23 パーセンタイル:70.38(Multidisciplinary Sciences)

Filamentous aggregates (amyloid fibrils) of the protein $$alpha$$-synuclein ($$alpha$$-Syn) are related to the pathogenesis of Parkinson's disease. To understand the pathogenesis mechanism of this disease, the mechanism of the amyloid fibril formation of $$alpha$$-Syn must be elucidated. As a first step toward this ultimate goal, dynamical behavior of $$alpha$$-Syn in the monomeric and the fibril states was investigated using quasielastic neutron scattering (QENS). Analysis of the QENS spectra of solution samples of $$alpha$$-Syn shows that diffusive global motions are observed in the monomeric state but largely suppressed in the fibril state. However, the amplitude of the side chain motion is shown to be larger in the fibril state than in the monomeric state. This implies that significant solvent space exists within the fibrils, which is attributed to the $$alpha$$-Syn molecules within the fibrils having a distribution of conformations. The larger amplitude of the side chain motion in the fibril state than in the monomeric state implies that the fibril state is entropically favorable.

論文

Spin hydrodynamic generation

高橋 遼*; 松尾 衛; 小野 正雄; 針井 一哉; 中堂 博之; 岡安 悟; 家田 淳一; 高橋 三郎*; 前川 禎通; 齊藤 英治

Nature Physics, 12, p.52 - 56, 2016/01

 被引用回数:74 パーセンタイル:95.51(Physics, Multidisciplinary)

Magnetohydrodynamic generation is the conversion of fluid kinetic energy into electricity. Such conversion, which has been applied to various types of electric power generation, is driven by the Lorentz force acting on charged particles and thus a magnetic field is necessary. On the other hand, recent studies of spintronics have revealed the similarity between the function of a magnetic field and that of spin-orbit interactions in condensed matter. This suggests the existence of an undiscovered route to realize the conversion of fluid dynamics into electricity without using magnetic fields. Here we show electric voltage generation from fluid dynamics free from magnetic fields; we excited liquid-metal flows in a narrow channel and observed longitudinal voltage generation in the liquid. This voltage has nothing to do with electrification or thermoelectric effects, but turned out to follow a universal scaling rule based on a spin-mediated scenario. The result shows that the observed voltage is caused by spin-current generation from a fluid motion: spin hydrodynamic generation. The observed phenomenon allows us to make mechanical spin-current and electric generators, opening a door to fluid spintronics.

論文

Structures of the troponin core domain containing the cardiomyopathy-causing mutants studied by small-angle X-ray scattering

松尾 龍人; 武田 壮一*; 小田 俊郎*; 藤原 悟

Biophysics and Physicobiology (Internet), 12, p.145 - 158, 2015/12

Troponin (Tn), consisting of three subunits, TnC, TnI, and TnT, is a protein that plays a major role in regulation of muscle contraction. Various mutations of Tn cause familial hypertrophic cardiomyopathy. Here we focus on the mutations E244D and K247R of TnT, which induce an increase in the maximum tension of cardiac muscle without changes in Ca$$^{2+}$$-sensitivity, and carried out small-angle X-ray scattering experiments on the Tn core domain containing the wild type subunits and those containing the mutant TnT in the absence and presence of Ca$$^{2+}$$. Changes in the overall shape induced by the mutations were detected for the first time by the changes in the radius of gyration and the maximum dimension between the wild type and the mutants. Analysis by model calculations shows that TnC adopts a dumbbell structure regardless of the mutations, and that the mutations change the distributions of the conformational ensembles so that the flexible N- and C-terminal regions of TnT become close to the center of the whole molecule.

論文

Barnett effect in paramagnetic states

小野 正雄; 中堂 博之; 針井 一哉; 岡安 悟; 松尾 衛; 家田 淳一; 高橋 遼*; 前川 禎通; 齊藤 英治

Physical Review B, 92(17), p.174424_1 - 174424_4, 2015/11

 被引用回数:22 パーセンタイル:71.67(Materials Science, Multidisciplinary)

We report the observation of the Barnett effect in paramagnetic states by mechanically rotating gadolinium (Gd) metal with a rotational frequency of up to 1.5 kHz above the Curie temperature. An in situ magnetic measurement setup comprising a high-speed rotational system and a fluxgate magnetic sensor was developed for the measurement. Temperature dependence of the observed magnetization follows that of paramagnetic susceptibility, indicating that any emergent magnetic field is proportional to the rotational frequency and is independent of temperature. From the proportionality constant of the emergent field, the gyromagnetic ratio of Gd is calculated to be -29 $$pm$$ 5 GHz/T. This study revisits the primordial issue of magnetism with modern technologies to shed new light on the fundamental spin-rotation coupling.

論文

Line splitting by mechanical rotation in nuclear magnetic resonance

針井 一哉; 中堂 博之; 小野 正雄; 松尾 衛; 家田 淳一; 岡安 悟; 前川 禎通; 齊藤 英治

Japanese Journal of Applied Physics, 54(5), p.050302_1 - 050302_3, 2015/05

 被引用回数:11 パーセンタイル:49.43(Physics, Applied)

Nuclear magnetic resonance (NMR) measurements for a nuclear spin 1/2 system in an external magnet field and mechanical rotation in kHz range are reported. NMR signals are measured by the synchronous rotation of a sample and a detector coil under the condition that the rotation axis is perpendicular to the external field. NMR line splits into two despite the system having a single Zeeman level separation. We analytically show that the splitting originates in the nuclear spin motion under mechanical rotation, and is determined by only the angular velocity of the rotation without any material parameters.

論文

Internal dynamics of F-actin and myosin subfragment-1 studied by quasielastic neutron scattering

松尾 龍人; 荒田 敏昭*; 小田 俊郎*; 中島 健次; 河村 聖子; 菊地 龍弥; 藤原 悟

Biochemical and Biophysical Research Communications, 459(3), p.493 - 497, 2015/04

 被引用回数:4 パーセンタイル:15.36(Biochemistry & Molecular Biology)

Various biological functions related to cell motility are driven by the interaction between the partner proteins, actin and myosin. To obtain insights into how this interaction occurs, the internal dynamics of F-actin and myosin subfragment-1 (S1) were characterized by quasielastic neutron scattering measurements on the solution samples of F-actin and S1. Contributions of the internal motions of the proteins to the scattering spectra were separated from those of the global macromolecular diffusion. Analysis of the spectra arising from the internal dynamics showed that the correlation times of the atomic motions were about two times shorter for F-actin than for S1, suggesting that F-actin fluctuates more rapidly than S1. It was also shown that the fraction of the immobile atoms is larger for S1 than for F-actin. These results suggest that F-actin actively facilitates the binding of myosin by utilizing the more frequent conformational fluctuations than those of S1.

論文

Observation of Barnett fields in solids by nuclear magnetic resonance

中堂 博之; 小野 正雄; 針井 一哉; 松尾 衛; 家田 淳一; 春木 理恵*; 岡安 悟; 前川 禎通; 安岡 弘志; 齊藤 英治

Applied Physics Express, 7(6), p.063004_1 - 063004_4, 2014/06

 被引用回数:40 パーセンタイル:84.91(Physics, Applied)

電気的に中性な物体であっても、回転する物体中の粒子には磁場が生じることが予言されている。この磁場をバーネット磁場という。我々は核磁気共鳴法が固体中に生じたバーネット磁場を測定できることを示す。我々は試料とNMR検出コイルを同じ早さで回転させると核磁気モーメントの符号を反映したNMRシフトが生じることを見いだした。この結果はバーネット磁場の直接的証拠である。NMRを用いたバーネット磁場の測定は未知の核磁気モーメントの符号を決定できる。

論文

Difference in hydration structures between F-actin and myosin subfragment-1 detected by small-angle X-ray and neutron scattering

松尾 龍人; 荒田 敏昭*; 小田 俊郎*; 藤原 悟

Biophysics, 9, p.99 - 106, 2013/07

Hydration structures around F-actin and myosin subfragment-1 (S1), which play central roles as counterparts in muscle contraction, were investigated by small-angle X-ray scattering (SAXS) and small-angle neutron scattering (SANS). The radius of gyration of S1 was evaluated to be 41.3 $$pm$$ 1.1 ${AA}$ for SAXS, 40.1 $$pm$$ 3.0 ${AA}$ for SANS in H$$_{2}$$O, and 37.8 $$pm$$ 0.8 ${AA}$ for SANS in D$$_{2}$$O, respectively. The values of the cross-sectional radius of gyration of F-actin were 25.4 $$pm$$ 0.03 ${AA}$ for SAXS, 23.4 $$pm$$ 2.4 ${AA}$ for SANS in H$$_{2}$$O, and 22.6 $$pm$$ 0.6 ${AA}$ for SANS in D$$_{2}$$O, respectively. Analysis showed that the hydration shell of S1 has the average density 10-15% higher than bulk water, being the typical hydration shell, while the hydration shell of F-actin has the average density more than 19% higher than bulk water, indicating that F-actin has a denser, unusual hydration structure. The results indicate a difference in the hydration structures around F-actin and S1.

論文

Dynamics of cardiomyopathy-causing mutant of troponin measured by neutron scattering

松尾 龍人; Natali, F.*; Plazanet, M.*; Zaccai, G.*; 藤原 悟

Journal of the Physical Society of Japan, 82(Suppl.A), p.SA020_1 - SA020_5, 2013/01

 被引用回数:2 パーセンタイル:21.48(Physics, Multidisciplinary)

トロポニンと呼ばれる蛋白質は、心筋の収縮を細胞内カルシウム濃度依存的に調節する。また、トロポニン分子内に起こるさまざまな変異が、肥大型心筋症等の疾患に繋がることが知られている。変異によってトロポニン分子の機能に異常が起こり、疾患へと繋がる。蛋白質が機能するためには、それを構成する原子の熱揺らぎ(ダイナミクス)が必須であると考えられているため、変異によるトロポニンの機能変化がダイナミクスの違いに起因する可能性が考えられる。そこで、変異によるトロポニンのダイナミクス変化を検出するために、野生型及び変異型(K247R)ヒト心筋トロポニンの溶液試料を用いて中性子散乱実験を行った。実験はフランスILLのIN13分光器を用いて行い、280Kから292Kの温度範囲を3Kごとに変化させて弾性散乱強度を測定した。得られたデータから見かけのバネ定数(蛋白質の柔らかさの指標)を計算すると、0.077N/m(野生型), 0.046N/m(変異型)となった。この結果は、変異によりトロポニン分子全体の柔軟性が増大することを示している。分子全体が過度に柔軟になることで、トロポニンのカルシウムシグナル伝達機構が正常に機能しなくなると考えられる。

論文

Isoscalar giant resonances in the Sn nuclei and implications for the asymmetry term in the nuclear-matter incompressibility

Li, T.*; Garg, U.*; Liu, Y.*; Marks, R.*; Nayak, B. K.*; Madhusudhana Rao, P. V.*; 藤原 守*; 橋本 尚信*; 中西 康介*; 奥村 瞬*; et al.

Physical Review C, 81(3), p.034309_1 - 034309_11, 2010/03

 被引用回数:94 パーセンタイル:97.47(Physics, Nuclear)

We have investigated the isoscalar giant resonances in the Sn isotopes using inelastic scattering of 386-MeV $$alpha$$ particles at extremely forward angles, including 0$$^{circ}$$. The strength distributions for various multipoles were extracted by a multipole decomposition analysis based on the expected angular distributions of the respective multipoles. We find that the centroid energies of the isoscalar giant monopole resonance (ISGMR) in the Sn isotopes are significantly lower than the theoretical predictions. In addition, the asymmetry term, $$K_{tau}$$, in the expression for the nuclear incompressibility has been determined from the ISGMR data in Sn isotopes and is found to be consistent with a number of indirectly extracted values for this parameter.

報告書

東海研究所における原子力施設等の解体に関する技術的検討

富居 博行; 松尾 浄*; 白石 邦生; 加藤 六郎; 渡部 晃三; 東山 豊; 長根 悟*; 塙 幸光*

JAERI-Tech 2005-017, 65 Pages, 2005/03

JAERI-Tech-2005-017.pdf:3.79MB

日本原子力研究所東海研究所では、JPDRが解体撤去されて以来、使命を終えた研究用原子炉施設,核燃料物質使用施設及び放射性同位元素等使用施設の解体が行われてきた。現在、解体対象の原子力施設は約20施設となっており、解体計画が重要な課題となっている。しかしながら、多様な原子力施設等に対応した解体に関する課題は必ずしも明確にはなってない。このことから、解体作業や法的手続を安全かつ確実に実施するために、これまでの解体経験や知見に基づく技術的な検討を行った。本報告書は、法的手続や解体作業に共通する事前評価及び廃棄物の取扱等について、これまでの解体経験から技術的課題を抽出し、検討したものである。今回の検討では、クリアランスの検認にかかわる事前評価や管理区域解除等の測定技術に幾つかの課題が見られた。

論文

Dynamic properties of lithium ions in lithium ceramics

井川 直樹; 大野 英雄; 長崎 正雅; 石井 慶信; 野田 健治; 渡辺 斉; 松尾 徹*; 五十嵐 一男*

Ceramic Transactions, Vol.27, p.135 - 156, 1992/00

Li$$_{2}$$Oを中心とするLi系セラミックス(Li$$_{2}$$O,Li$$_{2}$$SiO$$_{3}$$,Li$$_{4}$$SiO$$_{4}$$,Li$$_{8}$$ZrO$$_{6}$$,Li$$_{8}$$PbO$$_{6}$$,LiAlO$$_{3}$$,Li$$_{5}$$AlO$$_{4}$$,Li$$_{9}$$N$$_{2}$$Cl$$_{3}$$など)中のリチウムイオンの動的挙動をパルス核磁気共鳴法、イオン伝導度測定ならびにレーザーラマン分光法により測定・解析した。2価陽イオンを含むMgOならびに1価陰イオンを含むLiFを添加するこにより、これらLi化合物中におけるリチウムイオンの拡散は著しく増大した。高温におけるラマンスペクトル線巾の増大ならびにスピン-格子緩和時間の減少はリチウムイオンの拡散と密接な関係を有する。分子動力学法計算機シミュレーションによるLi$$_{2}$$O中でのリチウムイオンの拡散挙動についても解析した。

口頭

Structural changes of troponin by cardiomyopathy-causing mutations

藤原 悟; 松尾 龍人; 松本 富美子; 小田 俊郎*; 武田 壮一*

no journal, , 

Various mutations in the regulatory proteins of muscle contraction, troponin (Tn), consisting of three subunits, TnC, TnI, and TnT, have been reported to cause familial hypertrophic cardiomyopathy. To elucidate the molecular mechanism of pathogenesis of these mutations, we focus on the mutations in the coiled-coil region of TnT, E244D and K247R, and performed small-angle X-ray scattering (SAXS) experiments on the solutions of Tn containing wild-type TnT, and those containing mutant TnT. It was shown that the structural changes of Tn are induced by these mutations. Analysis by molecular modeling suggested that these changes arise from the changes in the conformational fluctuations rather than distinct structural changes.

口頭

JSFRのPLOHS時の事象推移の検討,1; PLOHS時におけるプラント応答過程の解析

松尾 英治*; 渡邊 素子*; 山田 由美*; 小山 和也*; 島川 佳郎*; 佐藤 充*; 神島 吉郎*; 横井 忍*; 山野 秀将; 鈴木 徹; et al.

no journal, , 

JSFRを対象としたレベル2PSAに資する目的でPLOHSの事象推移を検討している。本報では、PLOHS発生後のプラント応答過程における事象進展の検討結果を報告する。

口頭

Dynamics of cardiomyopathy-causing mutant of troponin observed by neutron scattering

松尾 龍人; Natali, F.*; Zaccai, G.*; 藤原 悟

no journal, , 

トロポニンと呼ばれる蛋白質は、心筋の収縮を細胞内カルシウム濃度依存的に調節する。また、トロポニン分子内に起こるさまざまな変異が、肥大型心筋症等の疾患に繋がることが知られている。変異によってトロポニン分子の機能に異常が起こり、疾患へと繋がる。蛋白質が機能するためには、それを構成する原子の熱揺らぎ(ダイナミクス)が必須であると考えられているため、変異によるトロポニンの機能変化がダイナミクスの違いに起因する可能性が考えられる。そこで、変異によるトロポニンのダイナミクス変化を検出するために、野生型及び変異型(K247R)ヒト心筋トロポニンの溶液試料を用いて中性子散乱実験を行った。実験はフランスILLのIN13分光器を用いて行い、280Kから292Kの温度範囲を3Kごとに変化させて弾性散乱強度を測定した。得られたデータから見かけのバネ定数(蛋白質の柔らかさの指標)を計算すると、0.077N/m(野生型), 0.046N/m(変異型)となった。この結果は、変異によりトロポニン分子全体の柔軟性が増大することを示している。分子全体が過度に柔軟になることで、トロポニンのカルシウムシグナル伝達機構が正常に機能しなくなると考えられる。

口頭

Internal dynamics of protein during amyloid fibril formation observed by neutron scattering

藤原 悟; 山田 武*; 松尾 龍人; 高橋 伸明; 蒲沢 和也*; 川北 至信; 柴田 薫*

no journal, , 

Amyloid fibrils, filamentous protein aggregates that are found as deposits in patients with various diseases, are related to pathogenesis of these diseases. Elucidation of the mechanism of the amyloid fibril formation is thus important for elucidation of the mechanism of pathogenesis. Since partial unfolding of a normal protein is likely to trigger the formation of the fibrils, characterization of "dynamics" of the protein should be important. Here we employ elastic incoherent neutron scattering (EINS) to characterize the dynamics of the protein during the amyloid fibril formation. We select hen egg-white lysozyme (HEWL) as a model system of the amyloid fibril formation. The EINS measurements on the solution samples of HEWL under the normal state and the amyloid-fibril states were performed with a high energy resolution near-backscattering spectrometer, DNA, installed at the materials and life science experimental facility at J-PARC, Tokai, Ibaraki, Japan. Differences in the dynamics were observed between HEWL under the normal states and the fibril state. The results of the detailed analysis is presented.

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