Studies on the subunit structure of textilotoxin, a potent presynaptic neurotoxin from the venom of the Australian common brown snake (Pseudonaja textilis). 2. The amino acid sequence and toxicity studies of subunit D.

Textilotoxin is a presynaptic neurotoxin in the venom of the Australian common brown snake, Pseudonaja textilis. It has the highest lethality and is structurally the most complex of any known snake venom neurotoxin. Reverse-phase HPLC was used to resolve textilotoxin into subunits A, B, C and D. Subunit D consists of two identical covalently linked polypeptide chains. Its sequence is now reported. It is an acidic, slightly glycosylated polypeptide of 133 amino acid residues in each chain. Although it is not itself neurotoxic, it was found to be essential for the neurotoxicity of textilotoxin.