Inactivation of α- and β-Thrombin by Antithrombin-III and Heparin

1976 ◽  
Vol 36 (03) ◽  
pp. 503-508 ◽  
Author(s):  
Raymund Machovich ◽  
György Blaskó ◽  
Anna Borsodi
Keyword(s):  
Heat Treatment ◽  
Complex Formation ◽  
Blood Circulation ◽  
Antithrombin Iii

SummaryInactivation of α- and β-thrombin by antithrombin-III and heparin was studied, since it had been suggested that two forms of thrombin exist with respect to heparin sensitivity (Machovich 1975b).It was found that the inactivation rates of α- and β-thrombin by antithrombin were different, namely α-thrombin was more sensitive to antithrombin than β-thrombin. Heparin facilitated the complex formation between α-thrombin and antithrombin-III, whereas β-thrombin inactivation was only slightly affected.Furthermore, heparin protected α-thrombin against the inactivating effect of heat, while β-thrombin lost its activity during the heat treatment.These findings suggest that the formation of β-thrombin in blood circulation may have an important role in thrombosis predisposition.

The Thrombin Protecting Function of a Complement Inhibitor in Human Plasma

1979 ◽  
Author(s):  
E.R. Podack ◽  
J.G. Curd ◽  
J.H. Griffin ◽  
H.J. Müller-Eberherd
Keyword(s):  
Complex Formation ◽  
Antithrombin Iii ◽  
Membrane Attack Complex ◽  
Protein S ◽  
Thrombin Time ◽  
Two Dimensional ◽  
Complement Inhibitor ◽  
Functional Studies ◽  
Sds Page ◽  
At Iii

S-protein (S) is a newly discovered 80,000 MW plosma glycoprotein. It functions as an inhibitor of the membrane attack complex of complement. We now wish to report that S also functions as thrombin protecting factor in coagulation; S forms a reversible complex with thrombin which is more resistant to inactivation by antithrombin III (AT III) than thrombin alone. An S-thrombin complex and on S-throm-bin-AT III complex were formed in clotted plasma and with isolated proteins as demonstrated by two dimensional Immunoelectrophoresis. Functional studies measuring the esterolytic or clotting activity of thrombin showed that S in the presence and absence of heparin decreased the rate of inactivation of thrombin by AT III. Similar results were observed using plasma. For example, in the presence of 0.04 u/ml heparin and 1.6 u/ml thrombin, the thrombin time of plasma depleted in S was 150 sec. as opposed to 15 sec. when the plasma was reconstituted with purified S. That this effect of S was due to a decreased inactivation of thrombin by AT III was demonstrated directly by SDS-PAGE analysis of plasma containing 125l-thrombin. In the presence of S the rate of formation of the 95,000 dalton 125I-thrombin-AT III complex was markedly decreased compared to the rate of complex formation in the S-depleted plasma. These data suggest that S may modulate the interactions of thrombin and AT III.

Plasma elimination kinetics for factor VII are independent of its activation to factor VIIa and complex formation with plasma inhibitors

2009 ◽  
Vol 101 (05) ◽  
pp. 818-826 ◽  
Author(s):  
Torben Elm ◽  
Mirella Ezban ◽  
Thomas Krogh ◽  
Ditte Karpf ◽  
Anne Steinø ◽  
...  
Keyword(s):  
Complex Formation ◽  
Antithrombin Iii ◽  
Factor Viia ◽  
Factor Vii ◽  
Elimination Kinetics ◽  
Inhibitor Complex ◽  
Α2 Macroglobulin ◽  
Clearance Mechanism ◽  
Deficient Mice

SummaryThe mechanism for the elimination of factor VII (FVII) from the circulation is unknown, just as it is unclear how activation of FVII to FVIIa and subsequent complex formation with antithrombin III (AT) or α2-macroglobulin (α2M) affects clearance. The possibility that the clearance mechanism involves activation and inhibitor complex formation as obligatory intermediate reactions is examined in this study. Human and murine sera were spiked with human FVIIa in the absence and presence of heparin and analysed for complex formation. Complex formation in vivo was studied after intravenous injection of 125I-VIIa in mice; and the pharmacokinetics (PK) of human and murine FVIIa was studied in normal mice. Furthermore, comparative PK studies were performed with FVII, FVIIa, active site blocked FVIIa and a preformed FVIIa-AT complex in normal and α2M-deficient mice. The data demonstrated that FVIIa-AT complexes and to a much lesser extent FVIIa-α2M-complexes accumulated in vivo after FVIIa administration. FVIIa-AT accounted for about 50% of total FVIIa antigen left in the circulation after 3 hours. All FVII derivatives studied including FVII, FVIIa and FVIIa-AT were cleared with similar rates suggesting an elimination kinetics which is unaffected by FVII activation and subsequent inactivation by plasma inhibitors.

Interaction of Thrombin with Antithrombin III and α2Macrogeobulin

1979 ◽  
Author(s):  
A. Takada ◽  
Y. Takada
Keyword(s):  
Complex Formation ◽  
Antithrombin Iii ◽  
Thrombin Activity ◽  
Presence And Absence ◽  
Hydrolysis Of

When one unit of thrombin was added to recalcified diluted plasma, more thrombin activity was shown in the presence of heparin than in its absence, but no difference was shown after two hour incubation. When one unit of thrombin was added to diluted plasma without the addition of Ca++, no difference in thrombin activities was shown in the presence and absence of heparin. When highly purified α2macroglobulin (α2M) and antithrombin III (ATIII) were used, thrombin activity was initially enhanced in the presence of either ATIII or ATIII, and quick inactivation of thrombin by ATIII regardless of the presence of heparin was observed. Electrophoresis shows that migrating patterns of ATIII depended upon amounts of heparin added to plasma, and ATIII migrated more to the anode with larger amounts of heparin. Thrombin-ATIII complex formed quickly in the undiluted recalcified plasma in the presence of heparin, but little complex formation was shown in the absence of heparin. When α2M was mixed with thrombin, and the mixture was added to TLMe at intervals, hydrolysis of TLMe was enhanced initially, then decreased quickly. α2M-thrombin complex seemed to be not as effective as free thrombin in the capacity to hydrolyze TLMe in contrast to α2M-trypsin or α2M-plasmin complex. α2M may be a primary inhibitor of thrombin in the plasma in the absence of heparin. In the presence of heparin, ATIII seems to be a primary inhibitor of thrombin.

Dissociation of antithrombin III-thrombin complex. Formation of active and inactive antithrombin III

Biochemistry ◽  
1981 ◽  
Vol 20 (1) ◽  
pp. 105-110 ◽  
Author(s):  
Michael J. Griffith ◽  
Roger L. Lundblad
Keyword(s):  
Complex Formation ◽  
Antithrombin Iii

Thrombin-Hirudin Complex Formation, Thrombin-Antithrombin III Complex Formation, and Thrombin Generation after Intrinsic Activation of Plasma

1994 ◽  
Vol 72 (03) ◽  
pp. 387-392 ◽  
Author(s):  
Siegfried Gallistl ◽  
Wolfgang Muntean
Keyword(s):  
Complex Formation ◽  
Thrombin Generation ◽  
Antithrombin Iii ◽  
Sudden Onset ◽  
Lag Phase ◽  
Clotting Time ◽  
Direct Inhibition ◽  
Recombinant Hirudin ◽  
Thrombin Antithrombin Iii Complex ◽  
Inhibition Of Thrombin

SummaryTo investigate the relative importance of direct inhibition of thrombin by complex formation and of inhibition of thrombin generation to the mechanisms by that unfractionated heparin (UH) and recombinant hirudin (rH) exert their anticoagulant effects, thrombin-antithrombin III complex (TAT) and thrombin-hirudin complex (THC) formation was compared with the generation of thrombin and prothrombin fragments 1 + 2 (F 1 + 2). Clotting was initiated by activation of citrated plasma in the absence or presence of UH or rH using partial thromboplastin, ellagic acid and calcium chloride. THC was determined by means of ELISA using specific antibodies to thrombin and rH.Activation of citrated plasma resulted in a sudden onset of thrombin generation after a lag phase of 2 min. Addition of 50 ng rH/ml plasma or 0.1 UH/ml plasma prolonged the clotting time to 3 min. While the peak of thrombin was only slightly decreased in hirudinized plasma, in heparinized plasma thrombin generation was significantly lower than in not anticoagulated plasma. This difference was more pronounced when the lag phase was prolonged to 5 min using 400 ng rH/ml plasma or 0.35 U UH/ml plasma. Using 1200 ng rH/ml or 0.65 U UH/ml to obtain a clotting time of 9 min only a small amount of thrombin could be detected in heparinized plasma, but hirudinized plasma still showed a high peak of thrombin. F 1 + 2 showed essentially the same pattern as thrombin. Prior to the onset of visible clot formation in all experiments using different concentrations of UH about the same values of TAT were observed. In contrast, when samples were anticoagulated with different amounts of rH, a dose dependent increase of THC was detected. When calculated from TAT and THC formation, much more thrombin was bound by rH than by AT III.Our experiments show that after intrinsic activation of plasma UH exerts its anticoagulant effect more by inhibiting thrombin generation, while rH suppresses thrombin generation to a much lesser extent but inhibits clotting more by direct inhibition of thrombin due to the formation of THC.

On the Complex Formation of Antithrombin III with Thrombin

1973 ◽  
Vol 30 (02) ◽  
pp. 280-283 ◽  
Author(s):  
B Binder
Keyword(s):  
Complex Formation ◽  
Human Serum ◽  
Blood Coagulation ◽  
Antithrombin Iii ◽  
Normal Human Serum ◽  
Molecular Weights ◽  
At Iii ◽  
Normal Human

SummaryBased on gelfiltration studies, the part of AT III which becomes bound to thrombin during the process of in vitro blood coagulation was calculated to be about 40% of total AT III. Complexes consisting of one AT III and one thrombin molecule could not be detected while fractions corresponding to molecular weights of about 190,000 Dalton show AT III as well as thrombin activities. The AT III - thrombin complex in normal human serum consists, therefore, of either 2 AT III and 2 thrombin molecules or of one AT III and 4 thrombin molecules.

scholarly journals Antithrombin-III-Hamilton, Ala 382 to Thr: an antithrombin-III variant that acts as a substrate but not an inhibitor of alpha-thrombin and factor Xa

Blood ◽  
1991 ◽  
Vol 77 (10) ◽  
pp. 2185-2189
Author(s):  
RC Austin ◽  
RA Rachubinski ◽  
FA Ofosu ◽  
MA Blajchman
Keyword(s):  
Complex Formation ◽  
Serine Proteases ◽  
Antithrombin Iii ◽  
Factor Xa ◽  
Biological Behavior ◽  
Form Complex ◽  
Free System ◽  
Reactive Center ◽  
Sds Page ◽  
At Iii

Antithrombin-III-Hamilton has been shown to be a structural variant of antithrombin-III (AT-III) with normal heparin affinity but impaired protease inhibitory activity. The molecular defect of AT-III-Hamilton is the substitution of Thr for Ala at amino acid residue 382. The plasma of affected individuals contains approximately equal quantities of normal AT-III and AT-III-Hamilton. When AT-III was isolated from the plasma of the propositus by heparin-Sepharose chromatography, it had identical mobility on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) to normal plasma-derived AT-III, under both reducing and nonreducing conditions. However, the AT-III-Hamilton species, separated from the propositus' normal AT-III by a combination of heparin-Sepharose and thrombin-Sepharose chromatography, had increased mobility on reductive SDS-PAGE compared with AT-III from the propositus isolated by heparin-Sepharose chromatography alone. Under nonreducing conditions this AT-III-Hamilton species had decreased mobility compared with AT-III from the propositus (or normal AT-III) isolated only by heparin-Sepharose chromatography. When incubated with either human alpha-thrombin or human factor Xa, this AT-III-Hamilton species was unreactive. Approximately 50% of the AT-III from the propositus isolated by heparin-Sepharose chromatography, when incubated with either human alpha-thrombin or factor Xa, did not form complex but was cleaved, presumably at the reactive center Arg393-Ser394. To further substantiate the biological behavior of this variant, AT-III- Hamilton polypeptides were synthesized in a cell-free system. This recombinantly produced AT-III-Hamilton, when incubated with either human alpha-thrombin or factor Xa, was cleaved by both these proteases, but did not show any complex formation. The results indicate that AT- III-Hamilton does not form a stable covalent inhibitory complex with these serine proteases but can be cleaved at the reactive center. Thus, the inhibition of serine proteases by their natural inhibitors (the serpins) involves at least two separate, but interrelated events; hydrolysis at the reactive center followed by complex formation. AT-III- Hamilton is capable of only the first of these events.

The Role of β-lactoglobulin in the primary phase of rennin action on heated casein micelles and heated milk

1974 ◽  
Vol 41 (3) ◽  
pp. 367-372 ◽  
Author(s):  
J. V. Wheelock ◽  
A. Kirk
Keyword(s):  
Heat Treatment ◽  
Complex Formation ◽  
Skim Milk ◽  
Primary Phase ◽  
Casein Micelles ◽  
Heated Milk ◽  
Β Lactoglobulin

SummaryIt has been shown that the inhibition caused by heat treatment, of the primary phase of rennin action on casein micelles, is dependent on the presence of β-lactoglobulin. The degree of inhibition increased with increasing amounts of added β-lactoglobulin for both heated casein micelles and heated skim-milk to a constant value. The results are fully consistent with the hypothesis that the inhibition is caused by complex formation between β-lactoglobulin and κ-casein when milk is heated.

scholarly journals Antithrombin-III-Hamilton, Ala 382 to Thr: an antithrombin-III variant that acts as a substrate but not an inhibitor of alpha-thrombin and factor Xa

Blood ◽  
1991 ◽  
Vol 77 (10) ◽  
pp. 2185-2189 ◽  
Author(s):  
RC Austin ◽  
RA Rachubinski ◽  
FA Ofosu ◽  
MA Blajchman
Keyword(s):  
Complex Formation ◽  
Serine Proteases ◽  
Antithrombin Iii ◽  
Factor Xa ◽  
Biological Behavior ◽  
Form Complex ◽  
Free System ◽  
Reactive Center ◽  
Sds Page ◽  
At Iii

Abstract Antithrombin-III-Hamilton has been shown to be a structural variant of antithrombin-III (AT-III) with normal heparin affinity but impaired protease inhibitory activity. The molecular defect of AT-III-Hamilton is the substitution of Thr for Ala at amino acid residue 382. The plasma of affected individuals contains approximately equal quantities of normal AT-III and AT-III-Hamilton. When AT-III was isolated from the plasma of the propositus by heparin-Sepharose chromatography, it had identical mobility on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) to normal plasma-derived AT-III, under both reducing and nonreducing conditions. However, the AT-III-Hamilton species, separated from the propositus' normal AT-III by a combination of heparin-Sepharose and thrombin-Sepharose chromatography, had increased mobility on reductive SDS-PAGE compared with AT-III from the propositus isolated by heparin-Sepharose chromatography alone. Under nonreducing conditions this AT-III-Hamilton species had decreased mobility compared with AT-III from the propositus (or normal AT-III) isolated only by heparin-Sepharose chromatography. When incubated with either human alpha-thrombin or human factor Xa, this AT-III-Hamilton species was unreactive. Approximately 50% of the AT-III from the propositus isolated by heparin-Sepharose chromatography, when incubated with either human alpha-thrombin or factor Xa, did not form complex but was cleaved, presumably at the reactive center Arg393-Ser394. To further substantiate the biological behavior of this variant, AT-III- Hamilton polypeptides were synthesized in a cell-free system. This recombinantly produced AT-III-Hamilton, when incubated with either human alpha-thrombin or factor Xa, was cleaved by both these proteases, but did not show any complex formation. The results indicate that AT- III-Hamilton does not form a stable covalent inhibitory complex with these serine proteases but can be cleaved at the reactive center. Thus, the inhibition of serine proteases by their natural inhibitors (the serpins) involves at least two separate, but interrelated events; hydrolysis at the reactive center followed by complex formation. AT-III- Hamilton is capable of only the first of these events.

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