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Hemorrhagic metalloproteinases from snake venoms
1Science Institute, University of Iceland, Reykjavik.
Insights
Snake venom metalloproteinases cause hemorrhage by destroying blood vessel walls. These toxins share structural similarities with mammalian reproductive proteins, suggesting potential shared biochemical activities with different physiological outcomes.
Area of Science:
- Biochemistry
- Toxicology
- Molecular Biology
Background:
- Crotalid envenomation frequently results in hemorrhage.
- Metalloproteinases in snake venom are the primary cause of this hemorrhage.
- These toxins degrade the extracellular matrix and basement membrane of capillaries.
Purpose of the Study:
- To review the history of hemorrhagic toxin research, focusing on Crotalus atrox.
- To outline structural similarities among venom hemorrhagic toxins.
- To describe the relationship between venom metalloproteinases and mammalian reproductive proteins.
Main Methods:
- Literature review of hemorrhagic toxin research.
- Analysis of structural studies on metalloproteinases.
- Comparison of venom metalloproteinases with mammalian reproductive proteins.
Main Results:
- Metalloproteinases are key factors in snake venom-induced hemorrhage.
- Hemorrhagic potency is influenced by the domains within these protein toxins.
- Structural homologs of venom metalloproteinases exist in mammalian reproductive systems.
Conclusions:
- Venom metalloproteinases cause hemorrhage via proteolytic destruction of vascular structures.
- Structural similarities suggest potential functional parallels between venom and reproductive metalloproteinases.
- Further research is needed to clarify the function of mammalian reproductive proteins with similar structures to venom toxins.
Abstract:
One of the more significant consequences of crotalid envenomation is hemorrhage. Over the past 50 years of investigation, it is clear that the primary factors responsible for hemorrhage are metalloproteinases present in the venom of these snakes. The biochemical basis for their activity is the proteolytic destruction of basement membrane and extracellular matrix surrounding capillaries and small vessels. These proteinase toxins may also interfere with coagulation, thus complementing loss of blood from the vasculature. Structural studies have shown that these proteinases are synthesized as zymogens and are processed at both the amino and carboxy termini to give the mature protein. The variety of hemorrhagic toxins found in snake venoms is due to the presence of structurally related proteins composed of various domains. The type of domains found in each toxin plays an important role in the hemorrhagic potency of the protein. Recently, structural homologs to the venom hemorrhagic metalloproteinases have been identified in several mammalian reproductive systems. The functional significance of the reproductive proteins is not clear, but in light of the presence of similar domains shared with the venom metalloproteinases, their basic biochemical activities may be similar but with very different consequences. This review discusses the history of hemorrhagic toxin research with emphasis on the Crotalus atrox proteinases. The structural similarities observed among the hemorrhagic toxins are outlined, and the structural relationships of the toxins to the mammalian reproductive proteins are described.