Hemostasis and fibrinolysis, the biological processes that maintain proper blood flow, are the consequence of a complex series of cascading enzymatic reactions.
Serine proteases involved in these processes are regulated by feedback loops, local cofactor molecules, and
serine protease inhibitors (
serpins). The delicate balance between proteolytic and inhibitory reactions in hemostasis and fibrinolysis, described by the coagulation,
protein C and fibrinolytic pathways, can be disrupted, resulting in the pathological conditions of
thrombosis or abnormal
bleeding. Medicine capitalizes on the importance of
serpins, using
therapeutics to manipulate the
serpin-
protease reactions for the treatment and prevention of
thrombosis and
hemorrhage. Therefore, investigation of
serpins, their cofactors, and their structure-function relationships is imperative for the development of state-of-the-art
pharmaceuticals for the selective fine-tuning of hemostasis and fibrinolysis. This review describes key
serpins important in the regulation of these pathways:
antithrombin,
heparin cofactor II,
protein Z-dependent
protease inhibitor, alpha(1)-protease inhibitor,
protein C inhibitor, alpha(2)-antiplasmin and
plasminogen activator inhibitor-1. We focus on the
biological function, the important structural elements, their known non-
hemostatic roles, the pathologies related to deficiencies or dysfunction, and the therapeutic roles of specific
serpins.