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Venombin A (EC 3.4.21.74, alpha-fibrinogenase, habutobin, zinc metalloproteinase Cbfib1.1, zinc metalloproteinase Cbfib1.2, zinc metalloproteinase Cbfib2, ancrod) is an enzyme. This enzyme catalyses the following chemical reaction

Selective cleavage of Arg- bond in fibrinogen, to form fibrin, and release fibrinopeptide A. The specificity of further degradation of fibrinogen varies with species origin of the enzyme

This enzyme is a thrombin-like enzyme from venoms of snakes of the viper/rattlesnake group. Examples include ancrod and batroxobin, two serine proteases from snakes that have been used in medical preparations.

Applications

Venombin A enzymes are the sole representatives of the defibrinogenating agent class of drugs, which by its protease action removes fibrinogen from the circulation. They are thought to act as an antithrombotic by depletion of fibrinogen. They are different from thrombin in that they only cleave fibrinogen alpha chain (those do cleave both chains are called venombin AB), which will end up only producing weak, urea-soluble microthrombi that is easily removed by plasmin. Their benefit in acute ischaemic stroke is not supported by available evidence.

Alternatively, batroxobin is also used as a topical hemostatic by its rapid local clot-expansion action.

References

1. Nolan C, Hall LS, Barlow GH (1976). "Ancrod, the coagulating enzyme from Malayan pit viper (Agkistrodon rhodostoma) venom". Part B: Proteolytic Enzymes. Methods in Enzymology. Vol. 45. pp. 205–13. doi:10.1016/s0076-6879(76)45020-6. ISBN 978-0-12-181945-3. PMID 1011992.
2. Stocker K, Barlow GH (1976). "The coagulant enzyme from Bothrops atrox venom (Batroxobin)". Part B: Proteolytic Enzymes. Methods in Enzymology. Vol. 45. pp. 214–23. doi:10.1016/s0076-6879(76)45021-8. ISBN 978-0-12-181945-3. PMID 1011993.
3. Markland FS, Kettner C, Schiffman S, Shaw E, Bajwa SS, Reddy KN, Kirakossian H, Patkos GB, Theodor I, Pirkle H (March 1982). "Kallikrein-like activity of crotalase, a snake venom enzyme that clots fibrinogen". Proceedings of the National Academy of Sciences of the United States of America. 79 (6): 1688–92. Bibcode:1982PNAS...79.1688M. doi:10.1073/pnas.79.6.1688. PMC 346045. PMID 7043462.
4. Simmons G, Bundalian M, Theodor I, Martinoli J, Pirkle H (November 1985). "Action of crotalase, an enzyme with thrombin-like and kallikrein-like specificities, on tripeptide nitroanilide derivatives". Thrombosis Research. 40 (4): 555–61. doi:10.1016/0049-3848(85)90292-0. PMID 2934864.
5. Itoh N, Tanaka N, Funakoshi I, Kawasaki T, Mihashi S, Yamashina I (June 1988). "Organization of the gene for batroxobin, a thrombin-like snake venom enzyme. Homology with the trypsin/kallikrein gene family". The Journal of Biological Chemistry. 263 (16): 7628–31. doi:10.1016/S0021-9258(18)68544-8. PMID 3163691.
6. Bell WR, Jr (1997). "Defibrinogenating enzymes". Drugs. 54 (Suppl 3): 18–30, discussion 30–1. doi:10.2165/00003495-199700543-00005. PMID 9360849. S2CID 25006039.
7. Kelton, JG; Smith, JW; Moffatt, D; Santos, A; Horsewood, P (1999). "The interaction of ancrod with human platelets". Platelets. 10 (1): 24–9. doi:10.1080/09537109976310. PMID 16801067.
8. Hao Z, Liu M, Counsell C, Wardlaw JM, Lin S, Zhao X (March 2012). "Fibrinogen depleting agents for acute ischaemic stroke". The Cochrane Database of Systematic Reviews (3): CD000091. doi:10.1002/14651858.CD000091.pub2. PMC 11503785. PMID 22419274.
9. Vu, TT; Stafford, AR; Leslie, BA; Kim, PY; Fredenburgh, JC; Weitz, JI (7 June 2013). "Batroxobin binds fibrin with higher affinity and promotes clot expansion to a greater extent than thrombin". The Journal of Biological Chemistry. 288 (23): 16862–71. doi:10.1074/jbc.M113.464750. PMC 3675619. PMID 23612970.

External links

• Venombin+A at the U.S. National Library of Medicine Medical Subject Headings (MeSH)

• Biology

• Antithrombotic enzymes
• EC 3.4.21
• Antihemorrhagics