南美響尾蛇毒素之特性及其作用之探討

Abstract

南美響尾蛇毒素經離子交換色層分析，可得到crotapotin及ㄧ鹼性磷脂?甲。分離純化過程，我們發現高操作液態色層分析(HPLC)效果較佳而且快速。在小雞二頸肌的毒性試驗中，crotapotin 無貝毒性及酵素活性，但可以提高鹼性磷脂?甲對神經突觸鍵前的抑制。南美響尾蛇毒素及crotapotin均穩定，而鹼性磷脂?甲本身在稀釋於生理溶液的情況下，易失去活性，尤其是外來的機械力量存在下，如振盪，通氧。顯示crotapotin對鹼性磷脂?甲有保護作用。肝素亦具有強陰電性，非但不能穩定鹼性磷脂?甲的活性，反而幹擾毒性的表現，可知毒素作用初期，二個次單位以正負價相互協同作用，提高了神經鍵前毒性。

Crotoxin, the main fraction of the venom of Crotalus durissus terrificus, consists of two subunits, which can be separated by ion-exchange chromatography and HPLC. Crotoxin PLA carries the phospholipase activity and possesses low toxicity, crotapotin has no enzymetic activity and is non-toxic by itself. The two subunits spontaneously reconstitute to form a complex having the properties of the native crotoxin. Diluted crotoxin PLA lost its presynaptic blocking activity rapidly in physiological solution when confronted with mechanic forces. This instability could be protected by crotapotin. Heparin reduced the toxicity of native toxin to half, and prevented the separated subunits to express toxicity when mixed. It indicated the interaction between crotoxin PLA and crotapotin to express its presynaptic inhibition is very important.