Plasmin and Kallikrein (PLM, PK, KLKB1)

Plasmin and plasma kallikrein are related but distinct serine proteases with major roles in vascular biology and inflammation. Plasmin, derived from plasminogen, is the principal enzyme responsible for fibrinolysis: it dissolves blood clots by degrading fibrin, and is also involved in tissue remodeling and cell migration. Plasma kallikrein (encoded by KLKB1) is activated from its precursor, prekallikrein, and is a key enzyme in the kallikrein-kinin system: it generates kinins (bradykinin) causing vasodilation and increased vascular permeability, and is involved in blood pressure regulation, coagulation, and inflammation. Both systems are tightly regulated, and dysregulation leads to clinically significant diseases including angioedema, thrombosis, and cardiovascular disease. Drugs targeting these enzymes are used to modulate clot formation/dissolution and to treat bradykinin-mediated swelling.

Other names

FibrinolysinPKKLKB1Fletcher factorKLKs

Plasmin inhibitors: block fibrin degradation, reduce bleeding; Plasmin activators: promote clot breakdown, treat thrombosis; Kallikrein inhibitors: prevent bradykinin release, reduce swelling (e.g., in hereditary angioedema); C1 esterase inhibitors: suppress contact system activation and bradykinin formation