| Project/Area Number |
17590256
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
General medical chemistry
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| Research Institution | Tokushima Bunri University |
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Principal Investigator |
TSUGE Hideaki Tokushima Bunri University, Institute for Health Sciences, Professor, 健康科学研究所, 教授 (40299342)
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| Co-Investigator(Kenkyū-buntansha) |
KATUNUMA Nobuhiko Tokushima Bunri University, Institute for Health Sciences, Professor, 健康科学研究所, 教授 (50035375)
SAKURAI Jun Tokushima Bunri University, Faculty of Pharmaceutical Science, Professor, 薬学部, 教授 (80029800)
MIYANO Masashi RIKEN Spring-8 Center Harima Institute, Structural Biophysics Laboratory, Chief Scientist, 構造生物物理, 主任研究員 (80332287)
AGO Hideo RIKEN Spring-8 Center Harima Institute, Structural Biophysics Laboratory, Senior Research Scientist, 構造生物物理, 主任研究員 (70360477)
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| Project Period (FY) |
2005 – 2006
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| Project Status |
Completed (Fiscal Year 2006)
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| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2006: ¥1,400,000 (Direct Cost: ¥1,400,000)
Fiscal Year 2005: ¥2,200,000 (Direct Cost: ¥2,200,000)
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| Keywords | sphingomyelinase / ceramide / apotosis / metal-binding / 金属結合 / 膜結合 / アポトーシス / 脂質ラフト / X線結晶構造解析 / 酵素 / 阻害剤 |
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| Research Abstract |
Sphingomyelinase (SMase) from Bacillus cereus (Bc-SMase) hydrolyzes sphingomyelin to phosphocholine and ceramide in a divalent metal ion-dependent manner. Bc-SMase is a homologue of mammalian neutral SMase (nSMase) and mimics the actions of the endogenous mammalian nSMase in causing differentiation, development, aging, and apoptosis. Thus Bc-SMase may be a good model for the poorly characterized mammalian nSMase. The metal ion activation of sphingomyelinase activity of Bc-SMase was in the order Co2+ > or = Mn2+ > or = Mg2+ >> Ca2+ > or = Sr2+. The first crystal structures of Bc-SMase bound to Co2+, Mg2+, or Ca2+ were determined. The water-bridged double divalent metal ions at the center of the cleft in both the Co2+-and Mg2+-bound forms were concluded to be the catalytic architecture required for sphingomyelinase activity. In contrast, the architecture of Ca2+ binding at the site showed only one binding site. A further single metal-binding site exists at one side edge of the cleft. Based on the highly conserved nature of the residues of the binding sites, the crystal structure of Bc-SMase with bound Mg2+ or Co2+ may provide a common structural framework applicable to phosphohydrolases belonging to the DNase I-like folding superfamily. In addition, the structural features and site-directed mutagenesis suggest that the specific beta-hairpin with the aromatic amino acid residues participates in binding to the membrane-bound sphingomyelin substrate.
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