Cobra venom reveals novel neurotoxin

The king cobra (Ophiophagus hannah) packs a venomous punch so potent that a single bite could kill up to 40 grown men or even an elephant.

Now researchers from an international team, including from Griffith University in Queensland, have characterised a novel toxin in king cobra venom, called haditoxin, and found it possesses some unique properties that could end up having correspondingly unique pharmacological applications.

Once the researchers examined the crystal structure of the toxin, they found it had a three-fingered protein fold which is unlike any other known toxin structure.

"This toxin is like a conjoined twin," said co-author of the paper, Dr S. Niru Nirthanan, from Griffith University, in a statement. "It is a relatively large complex made up of two identical protein molecules known as three-finger toxins linked together."

They also found that it could affect both neuron and muscle receptors, causing paralysis and respiratory failure.

"We know that the family of three-finger toxins display diverse biological actions on the human nervous system, cardiovascular system and blood clotting. Some have directly led to the development of compounds with potent analgesic and blood pressure reducing properties – so it is likely that haditoxin in its ‘conjoined twin’ state or as individual components will offer us more novel insights," said Nirthanan.

Other drugs developed from venoms include the blood pressure medication, Captopril, and the anti-clotting drug, Eptifibatide.

Given the toxin's unique pharmacology, it might also find application as a molecular probe.

"Because of the high specificity of these toxins, haditoxin may also be useful as a ‘molecular probe’ which will help us study neurotransmitter receptors and their role in disease," said Nirthanan.

The study was published as the "Paper of the Week" in the Journal of Biological Chemistry.