U. Haddeland et al., FREEZE-DRIED FIBRINOGEN OR FIBRINOGEN IN EDTA STIMULATE THE TISSUE-TYPE PLASMINOGEN ACTIVATOR-CATALYZED CONVERSION OF PLASMINOGEN TO PLASMIN, Blood coagulation & fibrinolysis, 5(4), 1994, pp. 575-581
Both soluble and insoluble fibrin stimulate the tissue-type plasminoge
n activator-catalysed conversion of plasminogen to plasmin. Whether fi
brinogen can exert a similar effect has been a controversial issue. Th
e present investigation shows that while fibrinogen purified by beta-a
lanine precipitation does not stimulate the tissue-type plasminogen ac
tivator-catalysed plasminogen activation, fibrinogen which has been ei
ther lyophilized or stripped of bound Ca2+ ions by EDTA chelation, sti
mulates this reaction. The data indicate that such procedures alter th
e molecular conformation of fibrinogen, and expose stimulatory sites w
hich are hidden in the native fibrinogen molecule. These results may e
xplain previous findings concerning the capacity of fibrinogen as a st
imulator of the tissue-type plasminogen activator-catalysed plasminoge
n activation. Since even slight alteration of the molecular structure
of fibrinogen leads to an increase in the tissue-type plasminogen acti
vator stimulation, the authors suggest that this can be used to test i
f the fibrinogen is in a native state.