Antithrombin
Previously called "Antithrombin III (AT3)"
There are also antithrombin I and II but AT3 is the medically relevant one.
Background
A serine protease inhibitor
Accounts for 70% to 75% of plasma capacity to inhibit coagulation
Produced by liver
MOA
Inactivates activated proteolytic factors by forming a stable complex
Binding is facilitated by heparin (accelerated by 1000 times)
Factors inactivated
- Thrombin (IIa) ← !!!
- Factor Xa ← !!!
- TF / VIIa complex
- Also
- IXa
- XIa
- XIIa
Also others:
- Kallikrein
- Plasmin
- Trypsin
- C1s subunit of enzyme C1 from classical complement pathway
Reference: WG21:p546, HH26:p603