Vanadyl (IV) and vanadate (V) binding to selected endogenous phosphate, carboxyl, and amino ligands; calculations of cellular vanadium species distribution.

Vanadium enters cells as vanadate (V) where it is reduced to vanadyl (IV), VO2+. Vanadate species at plasma pH, H2VO4-, and HVO4(2-) are referred to as VO3-. To gain an insight into the subcellular vanadium distribution we measured the binding of VO3- and VO2+ to extra- and intracellular ligands, and calculated free and bound fractions of these ions for expected in vivo conditions.

Purification and properties of an antiactivator fraction from bovine serum.

A method is described for the purification of antiactivator from bovine euglobulin-free serum by means of gelfiltration and ion exchange chromatography. The purified antiactivator has no antifibrinolytic activity. It has a molecular weight of about 115,000 and it appears to be a gamma globulin.

The binding of diiodosalicylate and flufenamate to the plasma antiactivator: analysis of chemical fibrinolysis.

The fibrinolytic effect of diiodosalicylate was expressed as apparent units urokinase. The dissociation constant of the urokinase-inhibitor complex is increased 19 times in the presence of 10(-2) M diiodosalicylate. The binding of diiodosalicylate to the antiactivator was estimated and the increase in free urokinase in the presence of diiodosalicylate was calculated.

Soluble fibrin complexes in early fibrin digests.

Early fibrin digests were analyzed in the ultracentrifuge and were found to contain compounds with molecular weights up to 3 X 10(6); these compounds are considered to be soluble fibrin complexes. Their similarity with intermediate polymers in inhibited clotting systems has been stressed. Their viscosity at low shear rates is extremely high; therefore, a rapid method to establish their presence in plasma would be the measurement of plasma and serum viscosity at low shear rates, moreover, they shorten the clotting time (thrombin time) of fibrinogen considerably.

Molar concentrations of fibrinolytic components, especially free fibrinolysin, in vivo.

The levels of fibrinogen and of profibrinolysin (plasminogen) in urokinase-treated plasma as a function of time of incubation were measured. The profibrinolysin concentration was estimated through its complete conversion to fibrinolysin and the inhibition of the enzyme by crystalline soybean trypsin inhibitor. The dissociation constant of the FL-STI complex was determined to be 7 times 10-9 M.

Characterization of the terminal degradation products of canine fibrinogen by plasmin.

Fibrinogen, isolated from canine plasma by the successive procedures of (1) freezing and thawing, (2) fractional precipitation with 25% saturated (HN4)2SO4 and (3) Sepharose 6B gel-filtration, had a molecular weight of 282 000 by the rapid sedimentation equilibrium method. However, a molecular weight for canine fibrinogen of 332 000, which is closer to that reported for human and bovine fibrinogens (340 000 plus or minus 20 000), was obtained from the sum of the molecular weights of the Aalpha, Bbeta and gamma chains, determined from dodecylsulfate gel electrophoretic patterns of reduced fibrinogen. Canine fibrinogen, subjected to proteolysis by urokinase-activated plasminogen for 24 h, contained degradation fragments D and E which were isolated by starch block electrophoresis and Sephadex G-200 gel-filtration.

Blood viscosity: influence of erythrocyte aggregation.

The addition of purified canine or bovine fibrinogen to suspensions of canine erythocytes in Ringer solution caused an increase in viscosity and the formation of aggregates of erythocytes. Both of these effects became increasingly pronounced as the fibrinogen concentration was raised, and they approached plateaus with 1 gram of fibrinogen per 100 milliliters. An increase in shear rate (or shear stress) reduced both the effect on viscosity and the aggregate size.