[Plasma kallikrein: new functions]

Area of Science:

• Biochemistry
• Hematology
• Immunology

Context:

• Recent literature review on human plasma kallikrein.
• Focus on newly identified functions and enzymatic activities.
• Exploration of its role in fluid-phase reactions.

Purpose:

• To discuss novel functions of human plasma kallikrein.
• To emphasize its role as an enzymatic activator of Hageman factor.
• To detail the feedback mechanism involved in this activation.

Summary:

• Plasma kallikrein activates Hageman factor via a feedback loop, initiating kinin formation, intrinsic clotting, and fibrinolysis.
• The molecule exhibits chemotactic activity for human neutrophils.
• Hageman factor acts as a proteinase with substrates including coagulation factor XI, plasminogen activator, and prekallikrein.

Impact:

• Underscores the significance of plasma kallikrein in initiating critical physiological cascades.
• Provides insights into the interconnectedness of coagulation, fibrinolysis, and kinin-kallikrein systems.
• Suggests potential therapeutic targets within these pathways.