| Project/Area Number |
10680625
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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 |
Biophysics
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| Research Institution | TOYAMA MEDICAL AND PHARMACEUTICAL UNIVERSITY |
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Principal Investigator |
KAWANO Keiichi Toyama Medical and Pharmaceutical University, Faculty of Pharmaceutical Sciences, Professor, 薬学部, 教授 (10136492)
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| Co-Investigator(Kenkyū-buntansha) |
KAWABATA Shunichiro Kyushyu University, Graduate School of Science, Associate Professor, 大学院・理学研究科, 助教授 (90183037)
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| Project Period (FY) |
1998 – 1999
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| Project Status |
Completed (Fiscal Year 1999)
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| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 1999: ¥1,500,000 (Direct Cost: ¥1,500,000)
Fiscal Year 1998: ¥2,000,000 (Direct Cost: ¥2,000,000)
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| Keywords | horseshoe crab / nematode / antimicrobial protein / NMR / solution structure / tachystatin / tachycitin / ASABF / カルシウムチャンネルブロッカー |
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| Research Abstract |
Many new structures and functions are expected to be found in invertebrate proteins because of the diversity of invertebrate animals. In particular, invertebrate defense systems, so-called innate immunity, include hemolymph coagulation and phenoloxidase-mediated melanization are induced by foreign substances, that result in the engulfment of invading microorganisms. These immobilized invaders are finally killed by antimicrobial substances released mainly from various hemocytes. In spite of the absence of immunoglobulin itself, the invertebrate hemolymph is capable of responding with a high degree of specificity against invaders. The authors focused on the new defense molecules in the invertebrate animals, horseshoe crab and nematode.
Tachycitin is an antimicrobial protein isolated from hemocytes of horseshoe crab, Tachypleus tridentatus. The solved structure is stabilized by five disulfide bridges, involving a three stranded antiparallel β-sheet. It is found that the N- and C-terminal are flexible and without regular secondary structures. Structural comparison between tachycitin and the known chitin-binding proteins reveals that the local structure (residues 40-60) of tachycitin is similar to that of plant chitin-binding proteins.
Tchystatin is also an antimicrobial protein isolated from hemocytes of horseshoe crab, Tachypleus tridentatus. From NOESY spectra analyses and structure calculations, the main element of secondary structure of tachystatin A is its triple- stranded β-sheet of classificaton +2x, -1 as its dominant structural motif. The three-dimensional structure of tachystatin A is similar with that of calcium channel blocker ω-agatoxin IVA found in venom of funnel web spider.
ASABF (A. suum antibacterial factor) is an antimicrobial protein found in the body fluid of the nematode Ascaris suum. The secondary structure of ASABF is composed of one α-helix and one β-sheet like as the motif of insect defensin.
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