| Project/Area Number |
10670227
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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 |
寄生虫学(含医用動物学)
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| Research Institution | Mie University |
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Principal Investigator |
YUDA Masao Mie Univ., Fac. of Med., Assistant, 医学部, 助手 (90293779)
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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 |
¥3,700,000 (Direct Cost: ¥3,700,000)
Fiscal Year 1999: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 1998: ¥2,800,000 (Direct Cost: ¥2,800,000)
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| Keywords | Coagulation / inhibitor / Rhodnius / factor IX / Prolixin-S / 吸血性昆虫 / 唾液腺 / 生理活性物質 |
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| Research Abstract |
Rhodnius prolixus is a blood-sucking Hemipteran insect which is known as a vector of American trypanosomiasis. This insect has several physiologically active molecules in its saliva that assist its blood-sucking behavior. We have already reported purification and the cDNA sequence of a salivary anticoagulant, prolixin-S, from this insect and demonstrated that prolixin-S was an inhibitor of the intrinsic Xase. We also reported that prolixin-S bound nitric oxide (NO) in its heme group as a vasodilator and a platelet aggregation inhibitor.
We further studied on its inhibitory mechanisms of the blood coagulation. We found prolixin-S specifically bound to factor IX/IXa in the presence of CaィイD12+ィエD1 ions. Light scattering and surface plasmon resonance (SPR) studies showed that prolixin-S interfered with factor Ix/IXa binding to the phospholipid membrane, indicating that prolixin-S inhibit Xase activity of factor IXa by interference with its Xase complex formation. Furthermore, reconstitution experiments showed that prolixin-S binding to factor IX strongly inhibited factor IXa generation by factor XIa. We also found that prolixin-S inhibited factor IXa generation by factor VIIa/tissue factor complex and factor IXalfa generation by factor Xa. These results suggests that prolixin-S inhibits both intrinsic and extrinsic coagulations by sequential inhibition of all coagulation pathways in which factor IX participates. It was also suggested that prolixin-S may bind to factor IX/IXa by recognizing conformational change of the Gla domain induced by CaィイD12+ィエD1 binding. To gain further understanding, we are now trying to locate the interactive sites using synthesized Gla-residue peptide.
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