Crotoxin (CTX) is the main toxic compound in the snake venom of the South American rattlesnake, Crotalus durissus terrificus.
Crotoxin is a heterodimeric beta-neurotoxin, composed of an acidic, non-toxic and non-enzymatic subunit (CA), and a basic, weakly toxic, phospholipase A2 protein (CB).
These researchers found that 60 per cent of the venom consisted of a neurotoxic substance, later referred to as crotoxin.
The CA subunit thereby blocks a part of the enzyme surface of phospholipase A2, resulting in an impossibility to be activated.
[6] The interface between CA and CB is formed by three tryptophan amino acids which play an important role in the stability of the crotoxin complex.
The relation between toxicity and enzyme activity is a result of the synergistic manner (Synergy) of action of both subunits.
[13] Another hypothesis is based on the specific binding with receptors and proteins to create intracellular enzyme dependent and independent reactions.
Membrane damage by the PLA2 activity allows PLA2 to enter cells and specifically bind to proteins and receptors either agonistic or antagonistic, inducing pharmacological effects non-enzymatically.
This blocking is achieved by a stabilization of the inactive form of the nicotinic acetylcholine receptors by the enzyme complex.
Together with the presynaptic acetylcholine inhibition, this post synaptic effect can lead to paralysis of the affected muscles.
[18] Low crotoxin levels produce an incomplete blockage of the acetylcholine receptor resulting in paresis, which is fully reversible.
[18] Crotoxin in C. durissus venom is a potent neurotoxin, which also causes renal- and myotoxic effects.
[23] In one study, Crotoxin has shown to improve the ocular alignment of a group of cross-eyed patients after injection.
[24] Clinical research has shown that the crotoxin complex and isolated CB have antigenic characteristics, which can stimulate antibody production.
Some studies have shown crotoxin to improve symptoms related to immune-associated disease and other conditions, including cancer.