Stocker K, Fischer H, Meier J, Brogli M, Svendsen L
Toxicon. 1987;25(3):239-52. doi: 10.1016/0041-0101(87)90253-4.
A single chain glycopeptide with a molecular weight of approximately 37,000, an isoelectric point of 3.0 +/- 0.2 and a carbohydrate content of approximately 20% was isolated from the venom of the southern copperhead Agkistrodon contortrix contortrix. It was capable of converting zymogen protein C in plasma of man and various vertebrates into its activated form, a serine proteinase which exerts an anticoagulant effect. Conversion of the zymogen protein C into the active proteinase was demonstrated by measuring the prolongation of the activated partial thromboplastin time due to proteolytic degradation of factors Va and VIIIa by the activation product, as well as by direct measurement of the generated enzyme activity by means of a synthetic chromogenic substrate. Intravenous injection of the venom protein C activator into rabbits caused prolonged activated partial thromboplastin time. Repeated subcutaneous injections led to formation of an antibody which formed, with purified protein C activator as well as with crude A. contortrix venom, a precipitating complex devoid of protein C activator potency. As revealed by activity measurements and by immunodiffusion experiments, the venoms of various A. contortrix, A. bilineatus subspecies contain similar protein C activators.
从南方铜头蝮蛇（Agkistrodon contortrix contortrix）的毒液中分离出一种单链糖肽，其分子量约为37,000，等电点为3.0±0.2，碳水化合物含量约为20%。它能够将人和各种脊椎动物血浆中的酶原蛋白C转化为其活化形式，即一种具有抗凝作用的丝氨酸蛋白酶。通过测量由于活化产物对因子Va和VIIIa的蛋白水解降解导致的活化部分凝血活酶时间延长，以及通过使用合成显色底物直接测量产生的酶活性，证明了酶原蛋白C向活性蛋白酶的转化。将毒液蛋白C激活剂静脉注射到兔子体内会导致活化部分凝血活酶时间延长。重复皮下注射会导致形成一种抗体，该抗体与纯化的蛋白C激活剂以及粗制的南方铜头蝮蛇毒液形成一种缺乏蛋白C激活剂效力的沉淀复合物。通过活性测量和免疫扩散实验表明，各种南方铜头蝮蛇、双线蝮蛇亚种的毒液含有相似的蛋白C激活剂。
