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Journal Articles

Nucleoside diphosphate kinase from psychrophilic ${it Pseudoalteromonas}$ sp. AS-131 isolated from Antarctic Ocean

Yonezawa, Yasushi*; Nagayama, Aiko*; Tokunaga, Hiroko*; Ishibashi, Matsujiro*; Arai, Shigeki; Kuroki, Ryota; Watanabe, Keiichi*; Arakawa, Tsutomu*; Tokunaga, Masao*

Protein Journal, 34(4), p.275 - 283, 2015/08

 Times Cited Count:4 Percentile:11.22(Biochemistry & Molecular Biology)

Nucleoside diphosphate kinase isolated from psychrophilic ${it Pseudoalteromonas}$ sp. AS-131 (ASNDK) was expressed in ${it Escherichia coli}$ and purified to homogeneity. Comparing to mesophilic NDK isolated from ${it Pseudomonas aeruginosa}$, ASNDK exhibited highly elevated thermolability: (1) ${it E. coli}$ expression at 37$$^{circ}$$C as a denatured insoluble form, and (2) 30$$^{circ}$$C lower optimum temperature of enzymatic activity. The subunit structure of ASNDK was suggested to be dimer, as in NDKs isolated from moderate halophiles.

Journal Articles

Reduction of salt-requirement of halophilic nucleoside diphosphate kinase by engineering S-S bond

Ishibashi, Matsujiro*; Uchino, Manami*; Arai, Shigeki; Kuroki, Ryota; Arakawa, Tsutomu*; Tokunaga, Masao*

Archives of Biochemistry and Biophysics, 525(1), p.47 - 52, 2012/09

 Times Cited Count:7 Percentile:21.08(Biochemistry & Molecular Biology)

Nucleoside diphosphate kinase (HsNDK) from Halobacterium salinarum requires salt at high concentrations for folding. A D148C mutant, in which Asp148 was replaced with Cys, was designed to enhance stability and folding in low salt solution by S-S bond. It showed increased thermal stability by about 10$$^{circ}$$C in 0.2 M NaCl over the wild type HsNDK. It refolded from heat-denaturation even in 0.1 M NaCl, while the wild type required 2 M NaCl to achieve the same level of activity recovery. This enhanced refolding is due to the three S-S bonds between two basic dimeric units in the hexameric HsNDK structure. Moreover, salt concentration dependency of heat-denaturation process and refolding process of the wild type and D148C mutant HsNDKs were investigated by the circular dichroism and native-PAGE analysis.

Journal Articles

Recent progress in the energy recovery linac project in Japan

Sakanaka, Shogo*; Akemoto, Mitsuo*; Aoto, Tomohiro*; Arakawa, Dai*; Asaoka, Seiji*; Enomoto, Atsushi*; Fukuda, Shigeki*; Furukawa, Kazuro*; Furuya, Takaaki*; Haga, Kaiichi*; et al.

Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.2338 - 2340, 2010/05

Future synchrotron light source using a 5-GeV energy recovery linac (ERL) is under proposal by our Japanese collaboration team, and we are conducting R&D efforts for that. We are developing high-brightness DC photocathode guns, two types of cryomodules for both injector and main superconducting (SC) linacs, and 1.3 GHz high CW-power RF sources. We are also constructing the Compact ERL (cERL) for demonstrating the recirculation of low-emittance, high-current beams using above-mentioned critical technologies.

Journal Articles

Dimer-tetramer assembly of nucleoside diphosphate kinase from moderately halophilic bacterium ${it Chromohalobacter salexigens}$ DSM3043; Both residues 134 and 136 are critical for the tetramer assembly

Tokunaga, Hiroko*; Izutsu, Kenichi*; Arai, Shigeki; Yonezawa, Yasushi; Kuroki, Ryota; Arakawa, Tsutomu*; Tokunaga, Masao*

Enzyme and Microbial Technology, 46(2), p.129 - 135, 2010/02

 Times Cited Count:6 Percentile:20.79(Biotechnology & Applied Microbiology)

Both wild-type nucleoside diphosphate kinase from moderately halophilc ${it Chromohalobacter salexigens}$ (CsNDK (GNE), GNE represents Gly134-Asn135-Glu136) and mutant CsNDK (ANE), both of which have a neutral amino acid at residue 134, were found to form a dimer. These constructs contain Glu136, which may also cause steric barrier and charge repulsion. A double mutant, CsNDK (ANT), having Thr at 136 resulted in stable tetrameric assembly, supporting the above notion. A mutant CsNDK (GNT) reverted, however, to a dimer again, indicating that the introduced Ala residue at 134th in the double mutant generated a hydrophobic cluster consisting of the Ala residues and thereby stabilized dimer-dimer association of CsNDK assembly, while Gly destabilized it due to the loss of this cluster. Based on these observations, it is evident that both residues 134 and 136 contribute to the subunit assembly of CsNDK.

Journal Articles

Residue 134 determines the dimer-tetramer assembly of nucleoside diphosphate kinase from moderately halophilic bacteria

Tokunaga, Hiroko*; Ishibashi, Matsujiro*; Arisaka, Fimio*; Arai, Shigeki; Kuroki, Ryota; Arakawa, Tsutomu*; Tokunaga, Masao*

FEBS Letters, 582(7), p.1049 - 1054, 2008/04

 Times Cited Count:17 Percentile:40.6(Biochemistry & Molecular Biology)

${it Halomonas}$ nucleoside diphosphate kinase (HaNDK) forms a dimeric assembly and ${it Pseudomonas}$ NDK (PaNDK) forms a tetrameric assembly. The mutation of Glu134 to Ala in HaNDK resulted in conversion of the native dimeric structure to the tetramer assembly. Conversely, the mutation of Ala134 to Glu in PaNDK leads to conversion from tetramer to dimer assembly, indicating that a single amino acid substitution at position 134 results in an alteration of the oligomeric structure of NDK. Modeling structure of HaNDK and PaNDK, based on the crystal structure of ${it Myxococcus}$ NDK, suggested sufficient repulsion by Glu134 to disrupt dimer-dimer interaction to form tetramer.

Oral presentation

Residue 134 determines the dimer-tetramer assembly of nucleoside diphosphate kinase from moderately halophilic bacteria

Tokunaga, Hiroko*; Ishibashi, Matsujiro*; Arisaka, Fimio*; Arai, Shigeki; Kuroki, Ryota; Yamaguchi, Rui*; Arakawa, Tsutomu*; Tokunaga, Masao*

no journal, , 

no abstracts in English

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