94 



E. KOCHVA 



Fig. 6 Striking sequence by Atractaspis engaddensis; sequence from film 

 (see text). 



it from the glands. Atractaspis, with its spade-shaped head, cannot 

 be milked the way other venomous snakes are; a special method had 

 to be devised as shown in Figure 9. 



Even today the biochemistry and pharmacology of the venom are 

 known for only a few species, with almost all the information 

 available originating from research with the venom of A. engaddensis. 



The toxicity of the venom varies among the species tested, the 

 most potent venom being that of A. engaddensis, exceeding by 40 

 times or more that of some other species (Table 1 ). It contains a set 





Fig. 7 Venom gland of Atractaspis engaddensis, cross section: M = 

 compressor muscle, L = lumen of venom gland, T = secretion tubules. 



of enzymes not unlike those of other venomous snakes, a quite 

 powerful hemorrhagin and a group of low-molecular weight toxins, 

 the sarafotoxins, named after the Hebrew name of A. engaddensis - 

 Saraf. When the venom was first fractionated by molecular sieving 

 on a Sephadex G-50 column, 7 protein peaks were obtained. The 

 first two contained high-molecular weight proteins with a 

 hemorrhagic factor and the enzyme L-amino acid oxidase; the third 

 peak showed phospholipase A, activity and peaks 5 and 6 contained 

 very low molecular weight peptides, which made up 40% of the 

 venom proteins and were highly toxic in i.v.-injected mice (Kochva 

 et al.. 1982). These fractions were further purified resulting in 

 several toxins characterised as sarafotoxins (SRTX), which showed 



Table 1 Toxicity of Atractaspis venoms, sarafotoxins. and mammalian 

 endothelins in mice, LD (ng/g b.w.) 



A. bibroni 



500 



A. dahomeyensis 



2000 



A. microlepidota 



>2000 



A. micropholis 



>3000 



A. engaddensis 



75 



Sarafotoxin-a 



10 



Sarafotoxin-b 



10 



Sarafotoxin-c 



300 



Sarafotoxin-d/e 



>2000 



Endothelin-1 



15 



Endothelin-3 



30 





