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Journal Articles

Seven cysteine-deficient mutants depict the interplay between thermal and chemical stabilities of individual cysteine residues in mitogen-activated protein kinase c-Jun N-terminal kinase 1

Nakaniwa, Tetsuko*; Fukata, Harumi*; Inoue, Tatsuya*; Goda, Masaki*; Nakai, Ryoko*; Kirii, Yasuyuki*; Adachi, Motoyasu; Tamada, Taro; Segawa, Shinichi*; Kuroki, Ryota; et al.

Biochemistry, 51(42), p.8410 - 8421, 2012/10

 Times Cited Count:15 Percentile:40.18(Biochemistry & Molecular Biology)

Protein kinase is a vital drug target for the treatment of a wide range of diseases. To investigate the effect of cysteine mutation on the function, stability and structure of kinase, free cysteines of c-Jun N-terminal kinase 1 (JNK1) were systematically removed by mutation. Two cysteine-destructed mutants in which three (M3) and seven (M7) cysteine residues are removed, yielded about 5 and 2 times than wild type JNK-1 (M0). SDS PAGE analysis showed that the aggregation was less in the case of M3 and M7. Thermal unfolding experiment of M0, M3 and M7 using by differential scanning calorimetry proceeded at least three state unfolding. Crystal structure of the M3 mutant was determined to 2.6 ${AA}$ resolution, which was identical to that of the wild-type. Consequently, due to the highest yield, its improved stability against aggregation and its structural similarity to the wild type, the M3 mutant is suitable for the use of further characterization of its function and structure.

Journal Articles

Combined high-resolution neutron and X-ray analysis of inhibited elastase confirms the active-site oxyanion hole but rules against a low-barrier hydrogen bond

Tamada, Taro; Kinoshita, Takayoshi*; Kurihara, Kazuo; Adachi, Motoyasu; Ohara, Takashi; Imai, Keisuke*; Kuroki, Ryota; Tada, Toshiji*

Journal of the American Chemical Society, 131(31), p.11033 - 11040, 2009/07

 Times Cited Count:52 Percentile:77.83(Chemistry, Multidisciplinary)

To help resolve long-standing questions regarding the catalytic activity of the serine proteases the structure of porcine pancreatic elastase has been analyzed by high-resolution neutron and X-ray crystallography. In order to mimic the tetrahedral transition intermediate a peptidic inhibitor was used. A single large crystal was used to collect room-temperature neutron data to 1.65 ${AA}$ resolution and X-ray data to 1.20 ${AA}$ resolution. Another crystal provided a low-temperature X-ray data set to 0.94 ${AA}$ resolution. The neutron data are to higher resolution than previously reported for a serine protease and the X-ray data are comparable with other studies. The neutron and X-ray data show that the hydrogen bond between His57 and Asp102 (chymotrypsin numbering) is 2.60 ${AA}$ in length and that the hydrogen-bonding hydrogen is 0.80-0.96 ${AA}$ from the histidine nitrogen. This is not consistent with a low-barrier hydrogen which is predicted to have the hydrogen midway between the donor and acceptor atom. The observed interaction between His57 and Asp102 is essentially a short but conventional hydrogen bond, sometimes described as a short ionic hydrogen bond. The neutron analysis also shows that the oxygen of the oxopropyl group of the inhibitor is present as an oxygen anion rather than a hydroxyl group, supporting the role of the "oxyanion hole" in stabilizing the tetrahedral intermediate in catalysis.

Journal Articles

Study on the behavior of oxygen atoms in swift heavy ion irradiated CeO$$_{2}$$ by means of synchrotron radiation X-ray photoelectron spectroscopy

Iwase, Akihiro*; Ono, Hirotaka*; Ishikawa, Norito; Baba, Yuji; Hirao, Norie; Sonoda, Takeshi*; Kinoshita, Motoyasu*

Nuclear Instruments and Methods in Physics Research B, 267(6), p.969 - 972, 2009/03

 Times Cited Count:33 Percentile:90.69(Instruments & Instrumentation)

To study the effects of swift heavy ion irradiation on cerium dioxide (CeO$$_{2}$$), CeO$$_{2}$$ sintered pellets were irradiated with 200 MeV Xe ions at room temperature. For irradiated and unirradiated samples, the spectra of X-ray photoelectron spectroscopy (XPS) were measured. XPS spectra for the irradiated samples show that the valence state of Ce atoms partly changes from +4 to +3. The amount of Ce$$^{3+}$$ state was quantitatively obtained as a function of ion-fluence. The relative amount of oxygen atom displacements, which are accompanied by the decrease in Ce valence state, is 3-5%. This value is too large to be explained in terms of elastic interactions between CeO$$_{2}$$ and 200 MeV ions. The experimental result suggests the contribution of 200 MeV Xe induced electronic excitation to the displacements of oxygen atoms.

Journal Articles

Temperature accelerated dynamics study of migration process of oxygen defects in UO$$_{2}$$

Ichinomiya, Takashi*; Uberuaga, B. P.*; Sickafus, K. E.*; Nishiura, Yasumasa*; Itakura, Mitsuhiro; Chen, Y.*; Kaneta, Yasunori*; Kinoshita, Motoyasu

Journal of Nuclear Materials, 384(3), p.315 - 321, 2009/02

 Times Cited Count:31 Percentile:89.51(Materials Science, Multidisciplinary)

We studied the migration dynamics of oxygen point defects in UO$$_{2}$$ which is the primary ceramic fuel for light-water reactors. Temperature accelerated dynamics simulations are performed for several initial conditions. Though the migration of the single interstitial is much slower than that of the vacancy, clustered interstitial shows faster migration than those. This observation gives us important insight on the formation mechanism of high-burnup restructuring, including planar defects and grain sub-division (the rim structure), found in UO$$_{2}$$.

Journal Articles

Clarification of the properties and accumulation effects of ion tracks in CeO$$_{2}$$

Sonoda, Takeshi*; Kinoshita, Motoyasu*; Ishikawa, Norito; Sataka, Masao; Chimi, Yasuhiro; Okubo, Nariaki; Iwase, Akihiro*; Yasunaga, Kazufumi*

Nuclear Instruments and Methods in Physics Research B, 266(12-13), p.2882 - 2886, 2008/06

 Times Cited Count:29 Percentile:87.21(Instruments & Instrumentation)

High-energy particle irradiation effects of CeO$$_{2}$$ is investigated using electron microscopy. It is found that ion track is formed only when the electronic energy transfer exceeds 16 keV/nm.

Journal Articles

Study on effects of swift heavy ion irradiation in cerium dioxide using synchrotron radiation X-ray absorption spectroscopy

Ono, Hirotaka*; Iwase, Akihiro*; Matsumura, Daiju; Nishihata, Yasuo; Mizuki, Junichiro; Ishikawa, Norito; Baba, Yuji; Hirao, Norie; Sonoda, Takeshi*; Kinoshita, Motoyasu

Nuclear Instruments and Methods in Physics Research B, 266(12-13), p.3013 - 3017, 2008/06

 Times Cited Count:52 Percentile:95.61(Instruments & Instrumentation)

Radiation damage of CeO$$_{2}$$ irradiated with 200MeV Xe is characterized by EXAFS and XPS measurement. It is found that oxygen deficiencies are created after the irradiation, and charge state of Ce is changed from +4 to +3.

Journal Articles

Study on effects of heavy ion irradiation on CeO$$_{2}$$ by using synchrotron radiation X-ray absorption spectroscopy; As a simulation study for radiation damage in high-burnup light water reactor fuels

Ono, Hirotaka*; Matsumura, Daiju; Nishihata, Yasuo; Mizuki, Junichiro; Ishikawa, Norito; Sonoda, Takeshi*; Kinoshita, Motoyasu*; Iwase, Akihiro*

Materials Research Society Symposium Proceedings, Vol.1043, p.179 - 183, 2008/00

CeO$$_{2}$$ thin films were irradiated with 200 MeV Xe ions. Effects of the irradiation were studied by using Extended X-ray Absorption Fine Structure (EXAFS) measurement at SPring-8 synchrotron radiation facility. EXAFS spectra for the irradiated thin films near the Ce K-edge show that the coordination number for oxygen atoms around Ce atom decreases and that the Ce-O Debye-Waller factor increases by the irradiation. The atomic distance between oxygen atom and Ce atom does not vary within the accuracy of EXAFS measurement. The effect of high density electronic excitation on the structure of CeO$$_{2}$$ is discussed.

Journal Articles

Study of irradiation induced restructuring of high burnup fuel; The New cross-over project (NXO) to study rim-structure formation

Kinoshita, Motoyasu*; Geng, H. Y.*; Chen, Y.*; Kaneta, Yasunori*; Iwasawa, Misako*; Onuma, Toshiharu*; Sonoda, Takeshi*; Yasunaga, Kazufumi*; Matsumura, Sho*; Yasuda, Kazuhiro*; et al.

Proceedings of 2006 International Meeting on LWR Fuel Performance (TopFuel 2006) (CD-ROM), p.248 - 254, 2006/10

The New Crossover Project (NXO) is studying effect of fission irradiation on fuel material that research activity is crossing over universities, national and private laboratories. Simulation studies are being performed to find principal and triggering processes of the rim-structure formation in high burnup LWR fuel pellet, using accelerator irradiation and computational calculations. Accelerator irradiation, high energy electron irradiation, fission energy particle beam and ion implantation (ragegas atoms) and combined overlapping irradiations are being performed. For the target of irradiation, CeO$$_{2}$$ isused as simulation of nuclear fuel. The initial results were such as planar structure made by Oxygen defects created by high energy electrons, and surface modification similar to grain-sub-division created by high fluence high energy particle irradiations.

Oral presentation

New cross-over project new engineering to control materials behaviour at high energy and high fluence irradiation, 6; Crystal lattice strain changes in irradiated fuel

Nakamura, Jinichi; Amaya, Masaki; Honda, Junichi; Hatakeyama, Yuichi; Fuketa, Toyoshi; Kinoshita, Motoyasu*

no journal, , 

Based on the micro-X-ray diffraction results, lattice parameters and diffraction peak broadenings (increase of FWHM of diffraction peak) of high burnup UO$$_{2}$$ pellets were measured. Crystallite diameter, which corresponds to subdivided grain diameter, and strain distribution between crystallites can be evaluated from the increase of FWHM of diffraction peak by using Willamson-Hall method. Basesd on these data, the crystal microstructural change during irradiation was examined and the effects of irradiation for microstructure.

Oral presentation

New cross-over project, "New engineering to control materials behavior at high energy and high fluence irradiation, 4; Development of experimental simulation technique using ion accelerator

Sataka, Masao; Ishikawa, Norito; Chimi, Yasuhiro; Okubo, Nariaki; Sonoda, Takeshi*; Matsumura, Sho*; Yasuda, Kazuhiro*; Yasunaga, Kazufumi*; Shiiyama, Kenichi*; Abe, Hiroaki*; et al.

no journal, , 

no abstracts in English

Oral presentation

New cross-over project, "New engineering to control materials behavior at high energy and high fluence irradiation", 5; Microstructure observation and analysis of irradiated ceramic compounds with the fluorite crystal structure

Matsumura, Sho*; Yasuda, Kazuhiro*; Yasunaga, Kazufumi*; Shiiyama, Kenichi*; Sonoda, Takeshi*; Abe, Hiroaki*; Iwai, Takeo*; Sataka, Masao; Ishikawa, Norito; Chimi, Yasuhiro; et al.

no journal, , 

no abstracts in English

Oral presentation

Numerical simulation of oxygen defects in UO$$_{2}$$

Ichinomiya, Takashi*; Nishiura, Yasumasa*; Itakura, Mitsuhiro; Kinoshita, Motoyasu

no journal, , 

Migration of oxigen vacancies/interstitials in uranium dioxide crystal is supposed to play a crucial role for the formation of rim-structure. However, the time-scale of oxide interstitial migration is beyond the feasibility of molecular dynamics simulations. In this presentation, we will present results of simulations which deal with longer time-scale.

Oral presentation

Mesoscopic simulation for the grain sub-division and the microstructural change of high burn-up fuels

Suzudo, Tomoaki; Fukuda, Yuka*; Kaburaki, Hideo; Itakura, Mitsuhiro; Kinoshita, Motoyasu*

no journal, , 

We have developed a mesoscopic model for the microstructural change of high burn-up fuels. In the current model, the accumulation of lattice defects, such as dislocations, is expressed by a small rotation of the matrix fragment, and it is examined if the grain sub-division be reproduced as the burn-up increases.

Oral presentation

Properties of interatomic potentials for CeO$$_{2}$$ and UO$$_{2}$$

Nakamura, Jinichi; Kaneta, Yasunori*; Chen, Y.*; Geng, H.*; Iwasawa, Misako*; Onuma, Toshiharu*; Kinoshita, Motoyasu

no journal, , 

no abstracts in English

Oral presentation

First principles study on formation enegitics of point defects in UO$$_{2}$$ and CeO$$_{2}$$

Nakamura, Jinichi; Chen, Y.*; Iwasawa, Misako*; Onuma, Toshiharu*; Kaneta, Yasunori*; Geng, H.*; Kinoshita, Motoyasu

no journal, , 

no abstracts in English

Oral presentation

Oxygen defects configration in UO$$_{2}$$; Dimer and planar ordering

Nakamura, Jinichi; Geng, H.*; Chen, Y.*; Kaneta, Yasunori*; Iwasawa, Misako*; Onuma, Toshiharu*; Kinoshita, Motoyasu

no journal, , 

Oral presentation

Recovery induced by high-density electronic excitations in CeO$$_{2}$$ pre-implanted with Xe ions

Yasunaga, Kazufumi*; Sonoda, Takeshi*; Yasuda, Kazuhiro*; Shiiyama, Kenichi*; Matsumura, Sho*; Sataka, Masao; Ishikawa, Norito; Chimi, Yasuhiro; Okubo, Nariaki; Iwase, Akihiro*; et al.

no journal, , 

Irradiation experiments were performed for CeO$$_{2}$$ using ion accelerators. CeO$$_{2}$$ were first pre-implanted with 2at.% Xe and furthermore heavily irradiated with high-energy heavy ions, and as a result restructuring of dislocation has been found.

Oral presentation

New cross-over project study, 7; Study on swift heavy ion-irradiation effects of simulation material of nuclear fuel "CeO$$_{2}$$" by means of synchrotron radiation

Ono, Hirotaka*; Maeda, Nobuhiro*; Nakagawa, Sho*; Zushi, Yoshihiro*; Iwase, Akihiro*; Baba, Yuji; Hirao, Norie*; Ishikawa, Norito; Chimi, Yasuhiro; Sataka, Masao; et al.

no journal, , 

X-ray absorption spectroscopy is applied for evaluation of heavy ion irradiation effects in sim-fuel CeO$$_{2}$$ in order to investigate the radiation damage of nuclear fuels bombarded by fission fragments. It is found that oxygen atoms are displaced via elastic displacement process, and the charge state of Ce changes from 4+ to 3+.

Oral presentation

New cross-over project study, 6; High density electronic excitation effects in Xe-ions-implanted fluorite ceramics as simulations of high burnup nuclear fuels

Sonoda, Takeshi*; Ishikawa, Norito; Sataka, Masao; Okubo, Nariaki; Yasunaga, Kazufumi*; Yasuda, Kazuhiro*; Shiiyama, Kenichi*; Matsumura, Sho*; Iwase, Akihiro*; Kinoshita, Motoyasu*

no journal, , 

In order to elucidate the radiation damage in nuclear fuel, simulation material CeO$$_{2}$$ has been irradiated with ions and its damage has been investigated. It is found that by 210MeV Xe irradiation subdivision of crystals is promoted, and Xe-preimplantation accelerates it.

Oral presentation

Status of reproduction of fuel behavior by computational studies and accelerator irradiation

Kinoshita, Motoyasu; Chen, Y.*; Sonoda, Takeshi*; Matsumura, Sho*; Nishiura, Yasumasa*; Iwase, Akihiro*; Nakamura, Jinichi

no journal, , 

no abstracts in English

39 (Records 1-20 displayed on this page)