[Interaction of human prothrombin with tissue thromboplastin].
The binding of 125I-labeled human prothrombin to native and papain-treated tissue thromboplastin in the presence of CaCl2 or EDTA was studied. The Scatchard plots for the protein binding suggest the presence at thromboplastin surface of two types of binding sites, high affinity [Kd(app) = 7.4.10(-8) M] and moderate affinity [Kd(app) = 7.9.10(-5) M]. The removal of Ca2+ did not influence the Kd (values for these) sites but markedly reduced their number. Proteolysis by papain caused a decrease in the affinity of high affinity sites without affecting the Kd values of the moderate affinity sites yet caused a proportional increase in the number of both high and moderate affinity sites in the presence of Ca2+. At low prothrombin concentrations a positive cooperativity of protein binding at high affinity sites in the presence of Ca2+ was observed.
Zubairov
D M
DM
Timerbaev
V N
VN
Kiselev
S V
SV
Kirshin
S V
SV
Soboleva
I V
IV
D002118:Calcium / Q000378:metabolism; D004492:Edetic Acid; D006801:Humans; D006868:Hydrolysis; D007202:Indicators and Reagents; D010206:Papain; D011516:Prothrombin / Q000378:metabolism*; D013925:Thromboplastin / Q000378:metabolism*
D007202:Indicators and Reagents; D011516:Prothrombin; D013925:Thromboplastin; D004492:Edetic Acid; D010206:Papain; D002118:Calcium
Vzaimodeĭstvie protrombina cheloveka s tkanevym tromboplastinom.