Effects of Agkadisin, a New Disintegrin Purified from snake Venom of Agkistrodon acutus, on Platelet Function

• Main Authors: Yu-Yin Chen, 陳譽尹
• Other Authors: Tur-Fu Huang
• Format: Others
• Language: zh-TW
• Published: 2004
• Online Access: http://ndltd.ncl.edu.tw/handle/76612917196084979125

碩士 === 國立臺灣大學 === 藥理學研究所 === 92 === By using column chromatography of DEAE-Sephadex A-50 and Mono Q5/5 cationic exchanger, a novel snake venom called Agkadisin from agkistrodon acutus was purified. Agkadisin inhibits aggregation of human washed platelets. When analyzed by SDS-PAGE, Agkadisin appears to be a double-chain polypeptide with a molecular mass of 29,000 Da. Upon reduction by β-mercaptoethanol, its mass was estimated to be about 15,000 Da. Agkadisin inhibits platelet aggregation induced by collagen or ADP in human platelet-rich plasma in a dose-dependent manner with IC50 of 5.6 μg/ml (192.8 nM) and 4.5 μg/ml (156.6 nM), respectively. In human platelet suspension, it also inhibits platelet aggregation induced by collagen and thrombin in a dose-dependent manner with IC50 of 4.1 μg/ml (142.8 nM) and 3.5 μg/ml (119.3 nM) respectively. Furthermore, Agkisdisin inhibits fibrinogen- induced aggregation of elastase-treated platelets with IC50 of 0.4 μg/ml (14.1 nM). Agkadisin showed significant inhibitory effect on the platelet binding of 7E3, a platelet GP IIb/IIIa mAb, but showed little effect on the binding of mAb raised against GP Ib or GP Ia/IIa. In Fura-2 loaded platelets, Agkadisin showed no effect on the intracellular calcium mobilization caused by collagen or thrombin. Agkadisin failed to inhibit the biosynthesis of TXB2 induced by collagen or thrombin in platelet suspension. Nevertheless, it appeared to inhibit TXB2 biosynthesis induced by collagen in platelet-rich plasma. In conclusion, Agkadisin inhibits platelet aggregation caused by collagen、thrombin, and ADP, while it has no effect on the cellular activation processes such as intracellular calcium mobilization and thromboxane A2 formation. On the other hand, Agkadisin blocks fibrinogen binding to elastase-treated platelets. Binding study using flow cytometry also demonstrates that Agkadisin acts on the final common pathway of platelet aggregation: the fibrinogen binding to platelet membrane GP IIb/III. Thus Agkadisin is a novel disintegrin belonging to dimeric disintegrin.