Alphabungarotoxin

alphabungarotoxin, also known as alpha-bungarotoxin (α-BTX), is a potent postsynaptic neurotoxin found in the venom of Bungarus species, most notably the banded krait (Bungarus multicinctus). It is a member of the three-finger toxin (3FTx) family and is classified as a long-chain alpha-neurotoxin, typically comprising about 66–74 amino acids and stabilized by five disulfide bonds.

Structure and mechanism: Alphabungarotoxin is a small, highly basic polypeptide with a characteristic three-finger fold. It acts as a competitive antagonist of nicotinic acetylcholine receptors at the neuromuscular junction, binding with high affinity to muscle-type and certain neuronal receptors and preventing acetylcholine from activating the receptor. This blockade disrupts signal transmission at the neuromuscular junction, leading to paralysis.

Occurrence and use: In venom, alphabungarotoxin contributes to rapid neuromuscular paralysis, enhancing the overall toxic effect. In laboratory research, it serves as a selective pharmacological tool to study nicotinic acetylcholine receptor subtypes. Researchers use isolated or labeled forms of the toxin to map receptor distribution and probe receptor–ligand interactions.

Safety and handling: Alphabungarotoxin is a powerful toxin and requires appropriate safety measures in research and clinical contexts. Effects are primarily peripheral, and exposure can cause paralysis and respiratory compromise. Medical intervention is required in envenomation cases, and handling of the toxin is restricted to trained personnel.