Waglerin-1 類似物之合成、生物活性及結構

Abstract

Trimeresurus wagleri又被稱為斑紋蝮蛇（Speckled pit viper)，普遍分佈在東南亞一帶地區，Waglerin-1是牠毒液裡的毒素之－，係由22個氨基酸所組成，其氨基酸序列為： 5 10 15 20 GGKPDLRPCHPPCHYIPRPKPR 其中有一個雙硫鍵。為瞭解其構造與生物活性之間的關係，首先以化學方法合成7個Waglerin-1的類似物來加以探討。 經由固相勝?自動合成儀逐步合成後，所得產物以切除試劑（cleavage reagent）除去所有保護基及樹脂（resin)，置於鹼性的醋酸銨（NH4OAc）溶液中（0.05 mg/ml)，以逆相高效率液相色層分析法追蹤及分離氧化態的Waglerin-1類似物。 這7個Waglerin-1類似物經氨基酸組成分析及質譜分析無誤後，做生物活性的測定及圓二極光譜分析，參考分子模擬的結果，發現影響這些類似物的毒性之主因可能在於其殘基電荷和／或其側鏈交互作用的被改變。此外，Waglerin-1致毒的活性區域（active site）極有可能就落在分子內雙硫鍵所約束形成的環形區域（loop）內，有待將來合成更多不同的類似物來做進一步的探討。

Trimeresurus wagleri. also known as the speckled pit viper, is abundant in south-eastern Asia. Waglerin-1 is one of the two main lethal components of T wagleri venom. The primary sequence of Waglerin-1 has been determined as followed: 5 10 15 20 GGKPDLPPCHPPCHYI PRPKPR There is an intramolecular disulfide bond within it. In order to understand the relationship between the structure and biological activity of Waglerin-1, a series of Waglerin-1 analogs replaced of the basic residues with Ala were synthesized by the method of automated solid-phase peptide synthesis and air-oxidation. After purification by HPLC, the synthetic Waglerin-1 analogs were characterized by amino acid analysis, ion-electrospray mass spectroscopy, bioassay, and circular dichroism in comparison with synthetic Waglerin-1. Refer to the results of molecular modeling, it suggests that the effect of the replaced charged residues of His-10 and His-14 to the toxicity of Waglerin-1 were most important. In addition, the active Site of Waglerin -1 is probably located in the loop region confined by the intramolecular disulfide bond. In the future, more Wagerin-1 analogs replaced in loop region can be synthesized for advanced study.