| Project/Area Number |
10559008
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| Research Category |
Grant-in-Aid for Scientific Research (B).
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| Allocation Type | Single-year Grants |
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| Section | 展開研究 |
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| Research Field |
広領域
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| Research Institution | Tokyo Noko University Tokyo University of Agriculture and Technology |
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Principal Investigator |
HASUMI Keiji Tokyo University of Agriculture and Technology, Faculty of Agriculture, Associate Professor, 農学部, 助教授 (20208474)
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| Co-Investigator(Kenkyū-buntansha) |
NAKAMURA Kazunori Torii Pharmaceutical Co., Research Laboratory, Senior Investigator, 研究所, 研究室長(研究者職)
KITANO Yoshikazu Tokyo University of Agriculture and Technology, Faculty of Agriculture, Assistant Professor, 農学部, 助手 (10302910)
CHIBA Kazuhiro Tokyo University of Agriculture and Technology, Faculty of Agriculture, Associate Professor, 農学部, 助教授 (20227325)
UCHIYAMA Hiroyuki Torii Pharmaceutical Co., Research Laboratory, Investigator, 研究所, 研究員
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| Project Period (FY) |
1998 – 2000
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| Project Status |
Completed (Fiscal Year 2000)
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| Budget Amount *help |
¥6,700,000 (Direct Cost: ¥6,700,000)
Fiscal Year 2000: ¥1,500,000 (Direct Cost: ¥1,500,000)
Fiscal Year 1999: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 1998: ¥4,000,000 (Direct Cost: ¥4,000,000)
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| Keywords | Cyclic peptides / Fibrinolysis / Prothrombin / Blood coagulation / PHBP / prothrombin / 環状ペピチド / 組溶系 |
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| Research Abstract |
The mechanism of plactin action : Two plasma factors that are essential for plactin-mediated prourokinase activation were identified by using plactin-Sepharose affinity chromatography. One was prothrombin, a coagulation factor, and the other was plasma hyaluronan binding protein(PHBP), a plasma serine protease with unknown physiological function. Plactin bound to prothrombin in a cooperative manner. The binding caused conformational change of the prothrombin molecule and modulated prothrombin activation by coagulation factor Xa. Prothrombinase-catalyzed prothrombin activation was inhibited, while activation by non-prothrombinase factor Xa was markedly enhanced. In the incubation of U937 cells with human plasma, the activation of prothrombin to thrombin was increased by plactin. The resulting thrombin cleaved prourokinase at Agr^<156>-Phe^<157>, yielding inactive two-chain urokinase(thrombin-cleaved urokinase ; tc-uPA/T). This urokinase species was activated to two-chain urokinase by cy
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statin-sensitive peptidase of U937 cells. In the presence of plactin, PHBP activated cellular benzamidine-sensitive protease, which in turn activated prourokinase on U937 cells. Thus, plactin enhances cellular fibrinolytic activity via two mechanisms, the prothrombin pathway and the PHBP pathway.
Pharmacological evaluation of plactin and its derivatives : We obtained following results evaluating 〜80 plactin derivatives. (1)Cyclotetrapeptide derivatives have comparable activity as compared with cyclopentapeptides. (2)Activity of cyclopeptides is dependent on one Lys or Agr and three to four hydrophobic residues. (3)Partial elimination of amido bond can retain activity, while solubility and bioavailability of the molecule are not improved. Plactin and one of its derivative with reduced amido bond were stable in plasma, and their half-life of these compounds in the circulation was >30 min, while these were not active when administered orally or intraperitoneally. In the thrombin-induced pulmonary embolism model mouse, these compounds showed prominent effects at an intravenous dose of 0.1 mg/kg. These results may partly be explained by the dual action of plactin, anticoagulation and fibrinolytic activation.
Development of chemical synthetic methods that are applicable to the synthesis of plactin derivatives : Several electrolytic oxidation/reduction conditions were tested to improve organic synthetic specificity and yield. Some conditions established were applicable to the modification of peptide compounds including plactins.
Identification of compounds that enhance fibrinolysis and/or suppress atherosclerosis : We identified several compounds with activity to enhance the fibrinolytic system and suppress pathways leading to formation of atherosclerosis. Less
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