Volume 09, No.4

理事長就任挨拶
Greetings from the Director General

吉良　爽　KIRA Akira

（財）高輝度光科学研究センター　理事長　Director General, JASRI

Pages 247 - 248 Download PDF (16.10 KB)

1. SPring-8の現状／PRESENT STATUS OF SPring-8

SPring-8運転・利用状況
SPring-8 Operational News

（財）高輝度光科学研究センター　研究調整部　Research Coordination Division, JASRI

Pages 249 - 250 Download PDF (14.21 KB)

論文発表の現状
Publications Resulting from Experiments at SPring-8

（財）高輝度光科学研究センター　利用業務部　User Administration Division, JASRI

Pages 251 - 252 Download PDF (24.71 KB)

2. ビームライン／BEAMLINES

共用ビームライン評価委員会の報告概要（平成15年度）
Report of the Public Beamline Review Committees in 2003

下村　理　SHIMOMURA Osamu

（財）高輝度光科学研究センター　研究調整部　Research Coordination Division, JASRI

Pages 253 - 256 Download PDF (25.70 KB)

3. 最近の研究から／FROM LATEST RESEARCH

ウシ心筋チトクロム酸化酵素のプロトンポンプ機構
−X線結晶学的、分子生物学的、赤外分光学的解析−
Proton Pumping Mechanism of Bovine Heart Cytochrome c Oxidase
– X-ray Crystallographical, Molecular Biological and Infrared Spectroscopical Analyses

吉川　信也　YOSHIKAWA Shinya

兵庫県立大学大学院　生命理学研究科　Graduate School of Life Science, University of Hyogo

Abstract: Improved X-ray structures of bovine heart cytochrome c oxidase (at 1.8/1.9 Å resolution in the fully oxidized/reduced states) show that the net positive charge created upon oxidation of the low-spin heme of the enzyme (heme a) drives the active proton transport from the interior of the mitochondria to Asp51 across the enzyme via a water channel and a hydrogen-bond network, located in tandem, and that the enzyme reduction induces proton ejection from the aspartate to the mitochondrial exterior. A peptide bond in the hydrogen-bond network critically inhibits reverse proton transfer through the network. A redox-coupled change in the capacity of the water channel, induced by the hydroxyfarnesylethyl group of heme a, suggests that the channel functions as an effective proton collecting region. The Asp51Asn mutation of the bovine enzyme abolishes its proton-pumping function without impairment of the dioxygen reduction activity. Infrared results indicate that the conformation of Asp51 is controlled only by the oxidation state of heme a. These results indicate that heme a drives the proton pumping process.

Pages 257 - 264 Download PDF (214.25 KB)

時分割X線小角散乱が明らかにする蛋白質の収縮と構造形成
Compaction and Structure Formation of Proteins Revealed by Time-Resolved Small Angle X-ray Scattering

高橋　聡　TAKAHASHI Satoshi^[1]、鵜澤　尊規　UZAWA Takanori^[2]、藤澤　哲郎　FUJISAWA Tetsuro^[3]

^[1]大阪大学　蛋白質研究所　Institute for Protein Research, Osaka University、^[2]京都大学大学院　工学研究科　Graduate School of Engineering, Kyoto University、^[3]（独）理化学研究所　播磨研究所　Harima Institute, RIKEN

Abstract: The compaction process in protein folding has not been characterized well due to experimental difficulties. The submillisecond-resolved observation system for small-angle X-ray scattering was developed and applied for the process of apomyoglobin folding. It was demonstrated that the secondary and tertiary structures are largely organized cooperatively; however, the initial folding phase involves a significant collapse of their main chain structures. A common folding mechanism was proposed, in which hydrophobic environments realized by the initial collapse prompts the subsequent formation of helical structures.

Pages 265 - 268 Download PDF (128.14 KB)

光合成の酸素発生に関わるタンパク質の立体構造を解明
−光合成植物の進化に新たな知見−
Elucidation of the Crystal Structure of the PsbP Protein Involved in the Oxygen Evolution in Photosynthesis

伊福　健太郎　IFUKU Kentaro

京都大学大学院　生命科学研究科／（独）理化学研究所　播磨研究所　Graduate School of Biostudies, Kyoto University / Harima Institute, RIKEN

Abstract: Photosynthesis is a multi-step reaction that utilizes light energy to convert carbon dioxide into sugar and generate oxygen as by-product. The first step of photosynthesis is the oxygen-evolving reaction performed by the protein-pigment complex called “photosystem II”, and PsbP is one of the protein subunits constituting photosystem II. Since PsbP exists only in higher plants and green algae, its existence has been the subject of inquiry in the process of plant evolution. In order to elucidate the origin and function of PsbP from its 3D structure, a high-resolution analysis based on multiple wavelength anomalous dispersion method using the X-ray of SPring-8 was conducted. The result showed that the structure of PsbP was not similar to any known structures in photosystem II from cyanobacteria, primitive organisms doing oxygenic photosynthesis. This research shows one aspect of the evolution of oxygenic photosynthetic organisms.

Pages 269 -274 Download PDF (298.96 KB)

2000Bに採択され2003Aに終了した長期利用課題の研究紹介（2）
Outline of Long-term Proposals (2000B-2003A)

（財）高輝度光科学研究センター　利用業務部　User Administration Division, JASRI

Page 275 Download PDF (452.72 KB)

硬X線マイクロビームを用いる顕微分光法の開発
Development of Spectromicroscopy with a Hard X-ray Microbeam

早川　慎二郎　HAYAKAWA Shinjiro

広島大学大学院　工学研究科　Graduate School of Engineering, Hiroshima University

Pages 275 - 284 Download PDF (452.72 KB)