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Some functional properties of teleost antithrombin
R Salte1, K Norberg, O R Odegaard
1AKVAFORSK (Institute of Aquaculture Research Ltd), As, Norway.
Thrombosis Research
|November 1, 1995
Summary
Fish antithrombin (AT) effectively inhibits thrombin, similar to human AT, with optimal activity at pH 7.8-8.4. Salmonid AT functions across a wide temperature range, unlike human AT, showing near-independence from temperature variations.
Area of Science:
- Biochemistry
- Comparative Physiology
- Enzymology
Background:
- Antithrombin (AT) is a key regulator of coagulation, primarily studied in humans.
- Understanding AT function in diverse species, like bony fish (Teleostei), provides insights into evolutionary adaptations of hemostasis.
Purpose of the Study:
- To investigate the functional characteristics of antithrombin from Atlantic salmon and rainbow trout.
- To compare the thrombin-antithrombin interaction in teleost species with the human system, focusing on cofactor (heparin) and environmental factor dependencies (pH, temperature).
Main Methods:
- In vitro assays measuring thrombin inactivation by purified antithrombin and diluted fish plasma.
- Enzyme-inhibitor kinetic studies were performed across varying pH, heparin concentrations, and temperatures.
Main Results:
- Teleost antithrombin effectively inactivates thrombin, with activity enhanced by heparin, similar to human antithrombin.
- Optimal activity for salmonid antithrombin-thrombin interaction occurred at pH 7.8-8.4.
- Teleost antithrombin-thrombin interactions demonstrated significant functional capacity at low temperatures (down to 3°C) and were largely temperature-independent, a key distinction from the human system.
Conclusions:
- Teleost antithrombin shares functional similarities with human antithrombin, particularly in heparin dependence and optimal pH range.
- The temperature independence of teleost thrombin-antithrombin interactions represents a significant functional adaptation to varying aquatic environments.
- These findings highlight the evolutionary plasticity of the coagulation system's regulatory mechanisms.