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安倍 諒治*; 名越 航平*; 新井 剛*; 渡部 創; 佐野 雄一; 松浦 治明*; 高木 秀彰*; 清水 伸隆*; 江夏 昌志*; 佐藤 隆博*
Nuclear Instruments and Methods in Physics Research B, 404, p.173 - 178, 2017/08
被引用回数：5 パーセンタイル：44.54(Instruments & Instrumentation)Molybdenum and zirconium obstruct the efficient recovery of minor actinides (MA(III): Am(III) and Cm(III)) by extraction chromatography; hence, the removal of these elements prior to MA(III) recovery is desirable. The use of an adsorbent impregnated with bis(2-ethylhexyl) hydrogen phosphate (HDEHP) for Mo and Zr decontamination was evaluated in this report. The adsorption/elution and column separation experiments showed that Mo and Zr in the simulated HLLW were selectively adsorbed on the particles, and that Mo was eluted by H
O. EXAFS analysis and SAXS patterns of the adsorbent containing Zr revealed that the Zr-HDEHP complex had a crystal-like periodic structure similar to the structure of the precipitate produced in the solvent extraction system. Micro-PIXE analysis revealed that distribution of the residual Zr on the adsorbent was uniform.
山口 繁生*; 上久保 裕生*; 栗原 和男; 黒木 良太; 新村 信雄*; 清水 伸隆*; 山崎 洋一*; 片岡 幹雄*
Proceedings of the National Academy of Sciences of the United States of America, 106(2), p.440 - 444, 2009/01
被引用回数：157 パーセンタイル：94.63(Multidisciplinary Sciences)Low barrier hydrogen bonds (LBHBs) have been proposed to play roles in protein functions, including enzymatic catalysis and proton transfer. Transient formation of LBHBs is expected to stabilize specific reaction intermediates. However, based on experimental results as well as on theoretical considerations, arguments against the importance of LBHB in proteins have been raised. The discrepancy is due to the absence of direct identification of the hydrogen atom position. Here, we show by high-resolution neutron crystallography of photoactive yellow protein (PYP) that a LBHB exists in a protein, even in the ground state. We identified 
87% (819/942) of the hydrogen positions in PYP, and demonstrated that the hydrogen bond between the chromophore and E46 is a LBHB. This LBHB stabilizes an isolated electric charge buried in the hydrophobic environment of the protein interior. We propose that in the excited state, the fast relaxation of the LBHB into a normal hydrogen bond is the trigger for photo-signal propagation to the protein moiety. These results give insights into the novel roles of LBHBs, as well as the mechanism of the formation of LBHBs.
山口 繁生*; 上久保 裕生*; 清水 伸隆*; 山崎 洋一*; 今元 泰*; 片岡 幹雄
Photochemistry and Photobiology, 83(2), p.336 - 338, 2007/03
被引用回数：6 パーセンタイル：14.59(Biochemistry & Molecular Biology)中性子結晶構造解析及び高分解能結晶構造解析のために、イェロープロテイン(PYP)の巨大結晶を作成した。巨大結晶は、硫酸アンモニウムを沈殿剤とし、さらに塩化ナトリウムを添加物として加えることにより成長した。得られたサイズは1.5
0.70.7mm
である。この結晶は、0.84
分解能までのX線回折斑点を与えた。構造解析の結果、213個(22.6%)の水素原子を観測することができたが、機能上重要な水素結合に関与する水素などは同定できず、中性子結晶構造解析の必要性が明らかとなった。重水から結晶化した試料を用いた予備的な測定から2.1までの中性子回折像を与えることが示された。
山口 繁生*; 上久保 裕生*; 栗原 和男; 黒木 良太; 新村 信雄*; 清水 伸隆*; 山崎 洋一*; 片岡 幹雄*
no journal, ,
Hydrogen bond dominates various physical properties in biological molecules and biological chemical reactions including proton transfer, hydrolysis, and so on. A special type of hydrogen bonds, the short hydrogen bond (SHB), has been proposed to have an important role in protein structure and function. The physical properties of SHBs, however, are still under debate. In the photoactive yellow protein (PYP), a light sensor protein, two SHBs near the chromophore have been revealed by X-ray crystallographic studies. The bond distances of the SHBs are modulated during the photo-reaction, resulting in the local proton transfer. From these facts, it can be postulated that these SHBs play a crucial role in the local proton transfer. Using high-resolution neutron crystallography in combination with high-resolution X-ray crystallography, we identified two deuterium atoms involved in two SHBs in PYP. One SHB, between the chromophore and E46, is identified as a low-barrier hydrogen bond (LBHB); the other, between the chromophore and Y42, is a short ionic hydrogen bond (SIHB). This is the first direct evidence of the coexistence of two distinct SHBs in the ground state of a protein. At the conference, we will present the neutron crystallographic structure and discuss the two SHBs in PYP.
渡部 創; 佐野 雄一; 新井 剛*; 松浦 治明*; 清水 伸隆*; 高木 秀彰*
no journal, ,
使用済核燃料からマイナーアクチノイドを回収するための技術として開発している抽出クロマトグラフィ法では、多孔質シリカ粒子にポリマーを被覆し、抽出剤を含浸させたものを吸着材として用いる。本研究では、ポリマー構造や抽出剤の含浸量等が吸着材内部に形成される錯体の局所構造や凝集体の形成に及ぼす影響をEXAFS及びSAXS実験によって調査した。その結果、吸着材系では溶媒抽出系と同じような抽出剤の凝集挙動は示さず、低酸濃度域においては周期構造を有する錯体を形成することが明らかになった。
