Structural and Conformational Similarity Between Synthetic Peptides of Curaremimetic Neurotoxins and Rabies Virus Glycoprotein

Antibodies were raised in rabbits against synthetic peptides corresponding to loop 2, the 'toxic' loop reacting with the acetylcholine-binding site on the nicotinic acetylcholine receptor, of curaremimetic neurotoxins and the structurally similar segment of the rabies virus glycoprotein. Some of the antibodies cross-reacted with the corresponding peptides confirming the structural similarity between the neurotoxin and glycoprotein peptides. A polyclonal antibody raised against a 29 residue glycoprotein peptide (175-203) in the presence of 0.1% sodium dodecyl sulfate reacted with native alpha-bungarotoxin and rabies virus. Circular dichroism spectroscopy of the 29 residue glycoprotein peptide and a 20 residue king cobra loop 2 peptide (25-44) revealed these peptides to be conformationally similar and composed predominantly of beta sheet structure. These results show the rabies glycoprotein segment is structurally and conformationally similar to neurotoxin loop 2. This similarity may confer on the glycoprotein the capability of interacting with the neurotoxin-binding site on the acetylcholine receptor.