Azemiopsin, a toxin obtained from the Azemiops feae viper venom, is a polypeptide that consists of 21 amino acid residues.
This resemblance is especially apparent in the C-terminal part, which includes alternating prolines and positively charged residues.
[1] However, the absence of disulfide bridges in azemiopsin makes this toxin less stable compared to other acetylcholine receptor-blocking peptides.
Azemiopsin is a high-affinity selective inhibitor of muscle-type nicotinic acetylcholine receptors and it can thus block synaptic transmission at the neuromuscular junction.
Additionally, it has shown an inhibitory effect on mouse muscle type α1β1εδ nicotinic acetylcholine receptor in nanomolar range (IC50 = 19 ± 8 nM).