Potentiation of Antithrombin III Activity by Sulphated Polysaccharides

1979 ◽  
Author(s):  
G. Kindness ◽  
W.F. Long ◽  
F.B. Williamson
Keyword(s):  
Antithrombin Iii ◽  
Ex Vivo ◽  
Anticoagulant Activity ◽  
Heparan Sulphate ◽  
Relative Effectiveness ◽  
Coagulation Factor ◽  
Factor X ◽  
Sulphated Polysaccharides ◽  
Molecular Rigidity ◽  
Cellulose Sulphate

Because of current interest in the mechanisms of antithrombin III-mediated anticoagulation by heparin, we examined the anticoagulant effectiveness of a number of other sulphated polysaccharides of relatively well-defined chemical structure using ex vivo assay systems. Our results suggest that heparan sulphate, cellulose sulphate, dextran sulphate, xylan sulphate, and a number of sulphated galactans derived from marine algae are able, like heparin, to potentiate antithrombin III inhibition of thrombin and activated coagulation factor X. Dermatan sulphate exerts anticoagulant activity which appears to be independent of antithrombin III. The relative effectiveness of these polymers as activators of antithrombin III may be related to their molecular rigidity.

scholarly journals Effect of a heparan sulphate with high affinity for antithrombin III upon inactivation of thrombin and coagulation factor Xa

1989 ◽  
Vol 262 (2) ◽  
pp. 651-658 ◽  
Author(s):  
M F Scully ◽  
V Ellis ◽  
N Shah ◽  
V Kakkar
Keyword(s):  
Rate Constant ◽  
Antithrombin Iii ◽  
Heparan Sulphate ◽  
Factor Xa ◽  
Coagulation Factor ◽  
Order Rate Constant ◽  
Pseudo First Order Reaction ◽  
High Affinity ◽  
Kinetics Of ◽  
Kinetics Of Inhibition

The kinetics of inhibition of human alpha-thrombin and coagulation Factor Xa by antithrombin III were examined under pseudo-first-order reaction conditions as a function of the concentration of heparan sulphate with high affinity for antithrombin III. The maximum observed second-order rate constant was, for the antithrombin III-thrombin reaction, 1.2 x 10(9) M-1.min-1 compared with 2.4 x 10(9) M-1.min-1 in the presence of high-affinity heparin. However, the maximum rate was catalysed by much higher concentrations of heparan sulphate (1.3 microM) than of heparin (0.025 microM). Differences were also observed in the maximal acceleration of the antithrombin III-Factor Xa interaction: 1.2 x 10(9) M-1.min-1 at 0.2 microM-heparin sulphate compared with 2.2 x 10(9) M-1.min-1 at 0.04 microM-heparin. The differences in properties of heparan sulphate and heparin were analysed by using the random bi-reactant model of heparin action [Griffith (1983) Proc. Natl. Acad. Sci. U.S.A. 80, 5460-5464]. It was observed that the apparent binding affinity for thrombin was higher for heparan sulphate (180 nM) than for heparin (14 nM). The rate constant for transformation of the antithrombin III-Factor Xa complex into irreversible product differed between heparan sulphate (96 min-1) and heparin (429 min-1). These properties of the high-affinity heparan sulphate may be of importance in consideration of a putative role in the control of intravascular haemostasis.

scholarly journals Inhibition by heparin-modulated antithrombin III of amidolysis catalysed by mβ-acrosin

1984 ◽  
Vol 217 (3) ◽  
pp. 721-725
Author(s):  
W F Long ◽  
F B Williamson
Keyword(s):  
Hyaluronic Acid ◽  
Molecular Mass ◽  
Antithrombin Iii ◽  
Heparan Sulphate ◽  
Relative Molecular Mass ◽  
Dextran Sulphate ◽  
Dermatan Sulphate ◽  
Arginine Residues ◽  
Cellulose Sulphate

Purified m beta-acrosin catalysed amidolysis of several p-nitroanilides with C-terminal arginine residues. Antithrombin III inhibited amidolysis catalysed by the enzyme. This effect of antithrombin III was potentiated by heparin, and to a modest extent by heparan sulphate, cellulose sulphate, dextran sulphate and xylan sulphate. De-N-sulphated heparin, de-N-sulphated N-acetylated heparin, heparin of low relative molecular mass, chondroitin 4-sulphate, chondroitin 6-sulphate, dermatan sulphate and hyaluronic acid were ineffective.

scholarly journals Anticoagulant activity of direct factor Xa inhibitors as a tool to ensure the effectiveness and safety of drugs intake

Kardiologiia ◽  
2019 ◽  
Vol 59 (11S) ◽  
pp. 28-35 ◽  
Author(s):  
T. V. Vavilova
Keyword(s):  
Clinical Presentation ◽  
Anticoagulant Activity ◽  
Oral Anticoagulants ◽  
Factor Xa ◽  
Coagulation Factor ◽  
Coagulation Cascade ◽  
Factor X ◽  
Direct Factor Xa Inhibitors ◽  
Thematic Review ◽  
Generation Test

The thematic review presents modern solutions using oral anticoagulants with a focus on direct coagulation factor X inhibitors. It contains information about the pharmacodynamics and pharmacokinetics of apixaban and rivaroxaban against the background of different drug intake regimens - twice and once per day. There are shown studies of concentration dynamics and the corresponding functional response, measured using the integral method - the thrombin generation test, which is widely used in scientific research to describe hemostatic processes based on an objective quantitative assessment of the thrombin formation – a key coagulation cascade serine protease. The logical relationship between the pharmacodynamics of anticoagulant action and the clinical presentation of the effectiveness and safety of drugs is traced. The review provides links to actual literature and current clinical guidelines.

Pentasaccharide and Orgaran® Arrest, whereas Heparin Delays Thrombus Formation in a Rat Arteriovenous Shunt

1993 ◽  
Vol 69 (01) ◽  
pp. 029-034 ◽  
Author(s):  
Gerard M T Vogel ◽  
Ronald G M van Amsterdam ◽  
Wim J Kop ◽  
Dirk G Meuleman
Keyword(s):  
Blood Circulation ◽  
Thrombin Generation ◽  
Antithrombin Iii ◽  
Ex Vivo ◽  
Thrombus Formation ◽  
Anticoagulant Activity ◽  
Rat Plasma ◽  
Arteriovenous Shunt ◽  
Methoxy Derivative ◽  
Local Deposition

SummaryThe mode of action of glycosaminoglycans (GAGs) towards thrombus formation in a rat arteriovenous shunt was studied by simultaneous examination of thrombus weight, platelet consumption and thrombin generation during 45 min of blood circulation. A comparison was made between the effects of heparin, the heparinoid Org 10172 (Orgaran®), and the chemically synthesized methoxy derivative of the antithrombin III binding pentasaccharide fragment of heparin (Org 31540).All three compounds inhibited thrombus growth by 30% at a dose of 80 anti-Xa U/kg i. v. when assessed after 15 min of circulation through the shunt. In addition, a systemic decrease of 27% of platelet numbers in the placebo group was inhibited by heparin and Orgaran® with 63% and by pentasaccharide with 48%. At a later stage, after 45 min of circulation, at comparable plasma anti-Xa levels, thrombi which had formed in the presence of Orgaran® or pentasaccharide, but not in the presence of heparin, became less or non thrombogenic. This non-thrombogenicity was reflected by i) an inhibition of the local deposition of [51Cr]platelets of 75% with Orgaran® and of 57% with pentasaccharide, and ii) an inhibition of ex-vivo thrombus-induced thrombin generation in pooled rat plasma of 67% with Orgaran® and of 52% with pentasaccharide (inhibition compared to placebo).Although the mechanism of inducing non-thrombogenicity of a (developing) thrombus by Orgaran® and pentasaccharide requires further investigation, the suppression of the local thrombin generation potency, measured by thrombus-induced thrombin generation in pooled plasma, is much more correlated with thrombus growth than systemic anticoagulant activity. This suppression is likely to be due to the anti-Xa activity, as reflected by the efficacy of the pure Xa inhibiting pentasaccharide. Limitation of thrombus growth adds to the prophylactic perspective of Orgaran® and pentasaccharide in preventing thrombosis.

scholarly journals The inhibition of thrombin-dependent positive-feedback reactions is critical to the expression of the anticoagulant effect of heparin

1987 ◽  
Vol 243 (2) ◽  
pp. 579-588 ◽  
Author(s):  
F A Ofosu ◽  
P Sie ◽  
G J Modi ◽  
F Fernandez ◽  
M R Buchanan ◽  
...  
Keyword(s):  
Antithrombin Iii ◽  
Anticoagulant Activity ◽  
Factor Xa ◽  
Factor V ◽  
Factor X ◽  
Intrinsic Pathway ◽  
Sulphated Polysaccharide ◽  
Pathway Activation ◽  
Pentosan Polysulphate ◽  
Inhibition Of Thrombin

Heparin catalyses the inhibition of two key enzymes of blood coagulation, namely Factor Xa and thrombin, by enhancing the antiproteinase activities of plasma antithrombin III and heparin cofactor II. In addition, heparin can directly inhibit the activation of Factor X and prothrombin. The contributions of each of these effects to the anticoagulant activity of heparin have not been delineated. We therefore performed experiments to assess how each of these effects of heparin contributes to its anticoagulant activity by comparing the effects of heparin, pentosan polysulphate and D-Phe-Pro-Arg-CH2Cl on the intrinsic pathway of coagulation. Unlike heparin, pentosan polysulphate catalyses only the inhibition of thrombin by plasma. D-Phe-Pro-Arg-CH2Cl is rapid enough an inhibitor of thrombin so that when added to plasma no complexes of thrombin with its inhibitors are formed, whether or not the plasma also contains heparin. Heparin (0.66 microgram/ml) and pentosan polysulphate (6.6 micrograms/ml) completely inhibited the intrinsic-pathway activation of 125I-prothrombin to 125I-prothrombin fragment 1 + 2 and 125I-thrombin. On the addition of thrombin, a good Factor V activator, to the plasma before each sulphated polysaccharide, the inhibition of prothrombin activation was demonstrable only in the presence of higher concentrations of the sulphated polysaccharide. D-Phe-Pro-Arg-CH2Cl also completely inhibited the intrinsic-pathway activation of prothrombin in normal plasma. The inhibitory effect of D-Phe-Pro-Arg-CH2Cl was reversed if thrombin was added to the plasma before D-Phe-Pro-Arg-CH2Cl. The inhibition of the activation of prothrombin by the three agents was also abolished with longer times with re-added Ca2+. Reversal of the inhibitory effects of heparin and pentosan polysulphate was associated with the accelerated formation of 125I-thrombin-antithrombin III and 125I-thrombin-heparin cofactor complexes respectively. These results suggest that the anticoagulant effects of heparin and pentosan polysulphate are mediated primarily by their ability to inhibit the thrombin-dependent activation of Factor V, thereby inhibiting the formation of prothrombinase complex, the physiological activator of prothrombin.

Factor XIIa inhibition by Infestin-4: in vitro mode of action and in vivo antithrombotic benefit

2014 ◽  
Vol 111 (04) ◽  
pp. 694-704 ◽  
Author(s):  
Yiming Xu ◽  
Tian-Quan Cai ◽  
Gino Castriota ◽  
Yuchen Zhou ◽  
Lizbeth Hoos ◽  
...  
Keyword(s):  
Mode Of Action ◽  
Ex Vivo ◽  
Anticoagulant Activity ◽  
Coagulation Factor ◽  
Kinetic Studies ◽  
Competitive Inhibitor ◽  
Human Albumin ◽  
Factor Xii

SummaryCoagulation factor XII (FXII) plays a central role in initiating the intrinsic cascade of blood coagulation. Purified recombinant Human Albumin- tagged Infestin-4 (rHA-Infestin-4) is a recently described FXIIa inhibitor that displayed strong anticoagulant activity without compromising haemostasis in several animal models. We pursued detailed in vitro characterisation of rHA-Infestin-4 and demonstrated that it is a competitive inhibitor of FXIIa with slow on and off rate constants for binding (kon =5x105 M-1s-1, koff =6x10–4 s-1), it can block FXIIa activation of its physiological substrates (plasma prekallikrein and FXI), and it can inhibit ellagic acid-triggered thrombin generation in plasma. Potency and selectivity profiling in enzyme assays suggest that rHAInfestin- 4 is indeed highly potent on FXIIa (IC50=0.3 ± 0.06, 1.5 ± 0.06, 1.2 ± 0.09 nM, for human, rat, and rabbit FXIIa, respectively) with at least >100-fold selectivity against factors IIa, Xa, IXa, XIa, VIIa, and plasma kallikrein in all three species. rHA-Infestin-4 dose-dependently and markedly reduced clot weight in the arteriovenous shunt thrombosis model in rats and rabbits, accompanied with minimal increase in cuticle bleeding times in either species. rHA-Infestin-4 treatment at 5 mg/kg in rabbit resulted in a 13% reduction in ex vivo FXa activity, demonstrating a modest off-target effect. In summary, our findings confirmed and extended previous reports that inhibition of FXIIa by rHA-Infestin-4 can produce strong antithrombotic efficacy while preserving haemostasis. Our comprehensive selectivity profiling, mode of action, and kinetic studies of rHA-Infestin-4 reveal limitations of this molecule and offer new perspectives on any potential effort of discovering novel FXIIa inhibitors.

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