|
| 日本放射光学会誌 Journal of JSSRR |
|
|
| Vol.33,No.1/Jan. 2020 |
|
|
 |
| 【表紙の説明】 ラジカルB12酵素エタノールアミンアンモニアリアーゼ（EAL）（(a), (b)）とジオールデヒドラターゼ（DD）（(c), (d)）における、基質結合によるアデノシルB12のアデノシル基とa側鎖の構造変化。a側鎖はラジカル発生後のリボース部の立体構造を安定に保つ。ただし、DDではすでに失活していたため基質結合前後でほとんど構造変化していない。 Fo-Fc omit maps around the adenosyl group of radical B12-dependent enzymes ethanolamine ammonia-lyase (EAL) and diol dehydratase (DD) complexed with adenosylcobalamin (AdoCbl) in the absence and presence of substrates (2-amino-1-propanol (2-AP) for EAL and 1,2-propanediol (1,2-PDO) for DD). EAL/AdoCbl (a), EAL/AdoCbl/2-AP (b), DD/AdoCbl (c), and DD/AdoCbl/1,2-PDO (d). The EAL/AdoCbl structure displayed that the C5´ atom of the adenosyl group remains on the cobalt atom with a Co-C distance of 3.00 Å (a). The Co-C bond was completely cleaved and the ribose group of the adenosyl group exists at the “catalytic position” where the adenosyl radical can abstract the hydrogen atom from the substrate molecule in the substrate-bound forms of EAL (b) and DD (d). Note that DD/AdoCbl actually represents suicidally-inactivated through undesirable side reactions during catalysis with contaminating substrate in the purified sample; the C5´ atom of the adenosyl group was placed adjacent to the catalytic position (c). In the case of EAL, structural shifts of the a-side chain and the adenosyl group of AdoCbl were observed after 10 min of soaking of substrate (a, b), although the electron densities of EAL/AdoCbl/2-AP are relatively ambiguous compared with the substrate-free structure; the a-side chain and the ribose group stay at the outward position and on the cobalt atom, respectively, in the resting pre-homolysis state, and they move to the inward position and to the catalytic position, respectively, in the post-homolysis state in the presence of substrate. |
| ・ |  |
| *次世代放射光への大きな期待 尾嶋正治（p.1）(1ページ、406k） |
|
| ・ |  |
| *硬X 線光電子分光と基礎物性測定により明らかにした価数の量子臨界現象 久我健太郎，松本洋介，大川万里生，中辻 知（p.2） *Quantum valence criticality probed by HAXPES and physical property measurements Kentaro KUGA, Yosuke MATSUMOTO, Mario OKAWA and Satoru NAKATSUJI (8 pages, 2,432k) |
|
| *X 線自由電子レーザーが誘起するナノプラズマ誕生の瞬間 熊谷嘉晃，福澤宏宣，永谷清信，和田真一，上田 潔（p.10） *The birth of a nanoplasma produced by an ultrashort hard-x-ray laser in xenon clusters Yoshiaki KUMAGAI, Hironobu FUKUZAWA, Kiyonobu NAGAYA, Shin-ichi WADA and Kiyoshi UEDA (9 pages, 1,263k) |
|
| *回転楕円ミラーによる軟X線FEL のサブミクロン集光と波長スケール集光への展望 本山央人，三村秀和（p.19） *Sub-1-μm focusing system based on an ellipsoidal mirror and the perspective on wavelength-scale focusing for soft x-ray free-electron lasers Hiroto MOTOYAMA and Hidekazu MIMURA (7 pages, 1,468k) |
|
| *透明セラミックス技術を用いた高解像度X線イメージング検出器の開発 亀島 敬，初井宇記（p.26） *Development of high-spatial resolution X-ray imaging detector by using transparent ceramic technology Takashi KAMESHIMA and Takaki HATSUI (7 pages, 2,161k) |
|
| *X線結晶構造に基づくB12補酵素がラジカル酵素反応を制御する仕組みの解明 柴田直樹，末吉由依，樋口芳樹，虎谷哲夫（p.33） *Direct participation of a peripheral side chain of a corrin ring in coenzyme B12 catalysis Naoki SHIBATA, Yui SUEYOSHI, Yoshiki HIGUCHI and Tetsuo TORAYA (10 pages, 2,774k) |
|
| ・ |  |
| *硬X 線光電子分光に関する国際会議HAXPES 2019報告 曽田一雄（p.43） (2 pages, 1,643k) |
|
| *佐々木泰三先生の思い出と二重の感謝 宮原恒昱（p.45） (3 pages, 246k) |
|
| *Professor Charles S. Fadley 追悼 大門 寛（p.48） (3 pages, 2,106k) |
| ・ |  |
 |
Back |