What enzyme cleaves plasminogen into plasmin during the clot dissolution process?

The enzyme that primarily cleaves plasminogen into plasmin during the clot dissolution process is tissue-type plasminogen activator (tPA). This enzyme is crucial for the fibrinolytic pathway, which is responsible for breaking down blood clots.

tPA is released by endothelial cells and is highly effective in converting plasminogen, an inactive precursor, into plasmin, the active enzyme that degrades fibrin, the structural component of blood clots. The process is essential for restoring normal blood flow after a clot has formed and is regulated to prevent excessive bleeding or inappropriate clotting.

While urokinase-type plasminogen activator (uPA) can also activate plasminogen, tPA is the more significant contributor in the context of the vascular system and occurs mainly in response to local needs in the presence of a clot.

The other options listed, such as Factor Xa and thrombin, play roles in the coagulation cascade, promoting clot formation rather than dissolution. Factor Xa is involved in converting prothrombin to thrombin, while thrombin is key in the conversion of fibrinogen to fibrin, which is essential for clot formation. Thus, their roles are primarily associated with clot creation rather than its breakdown.