Cerastocytin - Function Overview

Function Overview

Snake venom contains toxins capable of causing death to the reptile’s prey in many various ways. Most of the toxins fall into one of the two categories: elapid (mainly neurotoxic) or viperid (mainly hemotoxic) toxins depending on the immediate cause of death. Elapid snakes cause prey to die from asphyxiation because the dominating neurotoxins inhibit cholinesterase activity, thereby leading to paralysis of all muscles, including the diaphragm. The immediate cause of death after bites of viperid snakes is a sudden drop in blood pressure or stroke as the hemotoxins, mostly prevalent in this type of venom, induce either extensive coagulation or bleeding. While snakes are categorized in this manner, venom of either type may include a number of toxic enzymes involved in neurotoxicity, hemotoxicity, nutrient digestion and other functions necessary to make the prey available for consumption.

While all hemotoxins leading to clot formation induce in platelet aggregation, they do so in various ways. For example, botrocetin, found in the venom of Bothrops jararaca, activates von Willebrand factor (vWF) by inducing it to bind to platelet glycoprotein Ib (GPIb) thereby providing the surface for initial platelet aggregation. In contrast, cerastocytin and cerastotin (from the venom of Cerastes cerastes), as well as thrombocytin (from Bothrops atrox) and many others, are serine proteases that function in a way very similar to thrombin. Like thrombin, these proteases are capable of inducing platelet aggregation, and some even fibrin clot formation, at nanomolar concentrations.