Summary
Brinase added to human plasma in vitro caused a decrease in fibrinogen concentration,
positive paracoagulation tests and formation of a friable clot in sequence. Agarose
gel filtration of these samples revealed the presence of fibrinogen derivatives both
larger and smaller than the parent molecule. Infusion of the enzyme in vivo resulted
in a decreased fibrinogen level, a prolonged thrombin time and an increase in fibrinogen
related antigen (FRA) in serum. The elution pattern of FRA in the plasma samples obtained
after infusion of Brinase was similar to that of the in vitro samples. The plasma
pool of fibrinogen was partially consumed by infusion of Brinase, but the turnover
of plasminogen remained unaffected. Purified plasminogen was partially degraded by
addition of the enzyme but this was not accompanied by a generation of proteolytic
activity. These findings confirm that Brinase induces a proteolytic degradation of
fibrinogen in plasma without activation of the plasminogen-plasmin system. Exposure
of polymerization site(s) in the fibrinogen molecule is probably responsible for the
reported clot promoting effect of the enzyme.
