Vampire bat salivary plasminogen activator exhibits a strict and fastidious requirement for polymeric fibrin as its cofactor, unlike human tissue-type plasminogen activator. A kinetic analysis.

摘要: The vampire bat salivary plasminogen activator (BatPA) is virtually inactive toward Glu-plasminogen in the absence of a fibrin-like cofactor, unlike human tissue-type (tPA) (the kcat/Km values were 4 and 470 M-1 s-1, respectively). In presence fibrin II, tPA BatPA activated with comparable catalytic efficiencies (158,000 174,000 BatPA's cofactor requirement was partially satisfied by polymeric I (54,000 s-1), but monomeric ineffective (970 s-1). By comparison, variety species markedly enhanced tPA-mediated activation Glu-plasminogen. Fragment X polymer 2-fold better 9-fold worse as for BatPA, respectively, relative to II. Fibrinogen, devoid plasminogen, 10-fold than fibrinogen rigorously depleted Factor XIII, fibronectin; stimulatory effect less-purified apparently due XIII. contrast, two preparations equally poor cofactors BatPA-mediated possessed only 23 4% two-chain tPA, hydrolyzing chromogenic substrate Spectrozyme tPA. However exhibited similar hydrolysis Our data revealed that displayed strict fastidious or Consequently, may preferentially promote plasmin generation during narrow temporal window formation dissolution.