Penetrability of orally toxic protein from cobra venom through the gut of a blowfly.

The oral toxicity of a radioiodinated toxic polypeptide isolated from a cobra snake venom as assayed by Sarcophaga falculata blowflies coupled with assays on competitive displacement have indicated that: (a) During 3--4 h 8% of the orally active toxin is able to pass through the digestive system of the fly; (b) the orally active toxin after passing the gut binds to body tissues. The strong affinity of the toxin to tissue membranes explains its absence in the insect's hemolymph following oral applications as well as injection. The removal of traces of phospholipase A, which is extremely toxic, by injection of the orally active toxin has significantly lowered its injection toxicity without affecting its oral toxicity, thus indicating the absence of any interaction with phospholipases in oral toxicity. This conclusion was supported by additional experimentation.