Antithrombin III Padua: a "new" congenital antithrombin III abnormality with normal or near normal activity, normal antigen, abnormal migration and no thrombotic disease

A "new" antithrombin III abnormality is described in four members of a family. The proposita is a 38 years old female who showed no thrombotic disease and the following laboratory pattern: normal routine clotting tests, normal or near normal AT III activity (chromogenic substrates S-2238 and Chromozym Th) both in plasma and in serum and in the presence or absence of heparin, slightly decreased antifactor Xa activity (chromogenic substrate S-2222), normal progressive antithrombin, normal AT III antigen but abnormal migration in the agarose-heparin bidimensional system. In the latter test, one major abnormal peak, less anodal than the normal counterpart, and a smaller, apparently normal peak, were seen. In agarose without heparin the pattern was similar to normal both in plasma and in serum. Heparin tolerance to heparin in vivo and in vitro was slightly increased but still within normal limits. The two sons and a paternal aunt showed the same pattern. The hereditary pattern seems therefore autosomal dominant. The abnormality described appears different from AT III Budapest. The toponym of antithrombin III Padua is proposed to define this peculiar abnormality.     

Changes of antithrombin III (AT III) in AT III deficient patients during long-term anticoagulant treatment

Antithrombin III deficient patients with manifest thromboembolic diseases need long term coumarin treatment. There are contradictory data on the change of AT III during this therapy. The authors observed 5 patients with severe AT III decrease type I, 3 with functional abnormality and 2 with a pathological heparin binding. AT III function was determined by the Gerendás-Rák method and with chromogenic substrate. AT III antigen was measured with Behring M-Partigen and Laurell rocket electrophoresis. Crossed immunoelectrophoresis was carried out in all patients. In patients with type I AT III decrease, AT III hasn't changed even in a long period of more than 10 years. In the other types AT III became normal. The pathological heparin binding wasn't changed.     

Fluctuation of thrombin-antithrombin III complex in patients with acute myocardial infarction: influence of low-dose heparin administration.

The haemostatic parameters were studied within 14 days of acute myocardial infarction (AMI) in 103 patients randomly allocated into a group receiving low-dose heparin or into a group treated without anticoagulants. Patients with isotopic evidence of deep vein thrombosis were excluded from the analysis. An important formation of thrombin-antithrombin III complex (TAT) in the plasma was detected in the early stage of the disease. It was accompanied by an activation of plasma intrinsic fibrinolysis (IF), an elevation of fibrinogen and its degradation products (FDP) and a reduction of extrinsic plasma fibrinolytic activity (EF) together with normal levels of factor X, antithrombin III (AT III), protein C and alpha-2-antiplasmin. Sequentially studies periods of the disease revealed a diminution of TAT complex concentration in the plasma on the seventh day of AMI together with a rise of the both plasma fibrinolytic activities (IF, EF) as well as an elevation of fibrinogen and its degradation products, returning to the initial values on the 14 day of AMI. In the patients treated with heparin the augmentation of TAT complex in the plasma was prolonged until the fifth day of AMI. Moreover, heparin administration was connected with significantly higher levels of AT III and protein C along with a lower concentration of factor X and FDP on the seventh day of the disease. The fluctuation of fibrinolytic activities (IF, EF) in the plasma was heparin-independent. The present results indicate that low-dose heparin treatment modulates the plasmatic fluctuation of TAT complex as well as factor X, AT III and protein C levels in patients with acute myocardial infarction.     

Heterogeneity of mammalian antithrombin III

Affinity chromatography on heparin-Sepharose was used to isolate two forms of antithrombin III(AT) from human, bovine, rabbit and rat blood plasma. The two isolated forms of AT are the major form. AT alpha, making up to 90% of the whole inhibitor molecule, and the minor form, AT beta (10% of AT). The molecular mass of AT beta in all mammalian species under study is by 3-5 kDa lower than that of AT alpha. The isoelectric point for bovine AT alpha lies within the range of 4.95-4.5, whereas that for AT beta--at 5.28-4.76. No significant differences in the progressive antithrombin activity of the major and minor forms of the bovine inhibitor were observed. In contrast, the heparin-cofactor activity of the AT beta-heparin complex exceeds that of the AT alpha-heparin complex--3-fold. The functional differences in the AT forms are due to the differences in their affinities for heparin. It was shown that AT beta exhibits a higher affinity for free and bound heparin.     

Anticoagulant activity of fucoidans from brown algae

The anticoagulant activity of polysaccharide fucoidans from 11 species of brown algae was studied. The anticoagulant activity was measured by the activated partial thromboplastin time (APTT), prothrombin time, and thrombin time. Inhibitory action of these fucoidans significantly varied from one species to another. Fucoidans from Laminaria saccharina and Fucus distichus exhibited high anticoagulant activity, while fucoidans from Cladosiphon okamuranus and Analipus japonicus were almost inactive. Other fucoidans exhibited intermediate inhibitory activity. The inhibitory effect of fucoidans on thrombin and factor Xa was investigated in the presence or in the absence of natural thrombin inhibitor, antithrombin III (AT III). In contrast to the best-studied anticoagulant, heparin, most of these fucoidans inhibited thrombin in the absence of AT III. In the presence of AT III the inhibitory effect of fucoidans considerably increased. In contrast to heparin, fucoidans weakly influenced factor Xa activity in the presence of AT III and their inhibitory effect was not observed in the absence of AT III. There was no correlation between the anticoagulant activities of this series of fucoidans and their anti-inflammatory action, studied earlier. It is suggested that these two types of fucoidan activities depend on different structural features of fucoidans. Results of this study demonstrate a possibility of preparation of fucoidans with high anti-inflammatory activity but low anticoagulant activity. Anticoagulant activity of the fucoidans did not exhibit direct dependence on the content of fucose, the other neutral sugars and sulfates; no dependence was also found between the anticoagulant activity and the structure of the backbone of their molecules.     

Antithrombin III-dependent anti-prothrombinase activity of heparin and heparin fragments

Heparin and heparin fragments in the molecular mass range 1,700-20,000 Da were examined for their ability to accelerate the antithrombin III (AT III)-dependent inhibition of human factor Xa and the prothrombin converting complex (prothrombinase) during human prothrombin activation. The prothrombinase reaction was modeled by a 3-parameter 2-exponential equation to determine the initial rate of prothrombin activation and the pseudo-first order rate constants of inhibition of prothrombinase and in situ generated thrombin activity. The catalytic specific activities of the heparins increased with increasing molecular size for both the inhibition of prothrombinase and factor Xa. A 10-fold increase over the entire Mr range was found. In contrast to results obtained by others (Ellis, V., Scully, M. F., and Kakkar, V. V. (1986) Biochem. J. 233, 161-165; Barrowcliffe, T. W., Havercroft, S. J., Kemball-Cook, G., and Lindahl, U. (1987) Biochem. J. 243, 31-37), all the heparins showed a 5-fold higher rate of inhibition of factor Xa when compared with the inhibition of prothrombinase, indicating that the factor Va-mediated protection of factor Xa from inhibition by AT III/heparin is independent of the molecular size of the heparin. Our original approach has also revealed a hitherto unrecognized phenomenon, namely, in addition to the accelerating effect of the heparins on the rate of formation of the inactive AT III-factor Xa complex, heparins with Mr greater than 4,500 reduce the initial rate of thrombin generation in the presence of AT III in a concentration-dependent way. We hypothesize that the formation of the dissociable ternary AT III-heparin-factor Xa complex results in a (partial) loss of factor Xa activity towards its natural substrate prothrombin.     

Interaction of pregnancy-associated plasma protein-A (PAPP-A) with coagulation: a bioassay for PAPP-A

The observation that pregnancy-associated plasma protein A (PAPP-A) concentrations are higher in plasma compared to serum obtained from the same patient, together with fact that PAPP-A binds to heparin, prompted us to study the interaction between PAPP-A and the clotting system. It was determined that pure PAPP-A inhibits thrombin-induced coagulation of citrated plasma. The presence of antithrombin III (AT III) was necessary since PAPP-A had no inhibitory effect on coagulation of AT III-depleted plasma. The effect of PAPP-A is thus similar to that of heparin. This property of PAPP-A was used to develop a bioassay. Thrombin-induced polymerization of purified fibrinogen was measured in a spectrophotometer. AT III is a weak inhibitor of polymerization, but its effect is magnified in the presence of PAPP-A or heparin. The residual thrombin activity, when plotted against the concentration of PAPP-A, gives a linear relationship. The assay conditions developed allow maximal sensitivity and reproducibility. The kinetics of inhibition due to PAPP-A and heparin was first order. With this bioassay, activities of PAPP-A molecules isolated by the same technique from different fetomaternal compartments were compared.     

Arginine residues are critical for the heparin-cofactor activity of antithrombin III.

A dilution/quench technique was used to monitor the time course of chemical modification on the heparin-cofactor (a) and progressive thrombin-inhibitory (b) activities of human antithrombin III. Treatment of antithrombin III (AT III) with 2,4,6-trinitrobenzenesulphonate at pH 8.3 and 25 degrees C leads to the loss of (a) at 60-fold more rapid rate than the loss of (b). This is consistent with previous reports [Rosenberg & Damus (1973) J. Biol. Chem. 248, 6490-6505; Pecon & Blackburn (1984) J. Biol. Chem. 259, 935-938] that lysine residues are involved in the binding of heparin to AT III, but not in thrombin binding. Treatment of AT III with phenylglyoxal at pH 8.3 and 25 degrees C again leads to a more rapid loss of (a) than of (b), with the loss of the former proceeding at a 4-fold faster rate. The presence of heparin during modification with phenylglyoxal significantly decreases the rate of loss of (a). Full loss of (a) correlates with the modification of seven arginine residues per inhibitor molecule, whereas loss of (b) does not commence until approximately four arginine residues are modified and is complete upon the modification of approximately eleven arginine residues per inhibitor molecule. This suggests that (the) arginine residue(s) in AT III are involved in the binding of heparin in addition to the known role of Arg-393 at the thrombin-recognition site [Rosenberg & Damus (1973) J. Biol. Chem. 248, 6490-6505; Jörnvall, Fish & Björk (1979) FEBS Lett. 106, 358-362].     

The role of heparin in the thrombin-antithrombin III reaction

The effect of heparin on the kinetics of inactivation of thrombin by antithrombin III (AT) has been investigated in order to distinguish between two possible mechanisms. Either (1) heparin activates AT to make it a (kinetically) more effective inhibitor, or (2) heparin makes thrombin more susceptible to inhibition by AT. The results were consistent only with mechanism 1. The experimental approach was to premix heparin with either thrombin or AT and then to measure the rate of association of the two proteins in the rapid-mixing stop-flow spectrophotometer. Reactions were followed spectrophotometrically by observing displacement of the dye proflavine from the active site of thrombin as AT binds. Only premixing AT with heparin accelerated the reaction compared to control (no heparin); the observed second-order rate constant was enhanced by a factor of 200–400. Premixing of thrombin with heparin was without effect on the rate of association with AT. If heparin was premixed with both proteins before reaction, the rate was as slow as the control, indicating that heparin bound to thrombin is actually inhibitory to the association of enzyme with activated AT.     

The in situ inhibition of prothrombinase-formed human alpha-thrombin and meizothrombin(des F1) by antithrombin III and heparin

The inhibition of thrombin by antithrombin III (AT III) and heparin has been studied in pure systems to determine the kinetics of inhibition during human prothrombin activation. The present study shows that prothrombinase-catalyzed prothrombin activation resulted in the generation of thrombin and meizothrombin(des F1). In the absence of heparin the second-order rate constants of the inactivation of both thrombin and meizothrombin(des F1) formed in the reaction mixture appeared to be identical, k = 3.7 X 10(5) M-1 min-1. The rate constant of inhibition of purified thrombin was 6.5 X 10(5) M-1 min-1. In the presence of heparin the decay of the amidolytic activity was biexponential and could be modeled by a four-parameter equation to determine the pseudo first-order rate constants of inhibition as well as the composition of the reaction with respect to the levels of thrombin and meizothrombin(des F1). The ratio of thrombin over meizothrombin(des F1) varied with the initial prothrombin concentration. Heparin catalyzed the AT III inhibition of thrombin but not meizothrombin(des F1) formed during the prothrombin activation. Thrombin, generated by (Xa-Va-phospholipid-Ca2+) was inhibited by AT III/heparin more slowly than purified thrombin, and the saturation kinetics of the inhibition with respect to AT III differed from those found with purified thrombin.     

The Linear Angiosperm Phylogeny Group (LAPG) III: a linear sequence of the families in APG III

The publication of the third Angiosperm Phylogeny Group (APG) classification (APG III. 2009. An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG III. Botanical Journal of the Linnean Society 161: 128–131) has resulted in the need for a revised systematic listing of the accepted families. This linear APG III (LAPG III) sequence of families is presented here. © 2009 The Linnean Society of London, Botanical Journal of the Linnean Society, 2009, 161 , 128–131.     

Mechanisms responsible for catalysis of the inhibition of factor Xa or thrombin by antithrombin using a covalent antithrombin-heparin complex

Covalent antithrombin-heparin (ATH) complexes, formed spontaneously between antithrombin (AT) and unfractionated standard heparin (H), have a potent ability to catalyze the inhibition of factor Xa (or thrombin) by added AT. Although approximately 30% of ATH molecules contain two AT-binding sites on their heparin chains, the secondary site does not solely account for the increased activity of ATH. We studied the possibility that all pentasaccharide AT-binding sequences in ATH may catalyze factor Xa inhibition. Chromatography of ATH on Sepharose-AT resulted in >80% binding of the load. Similar chromatographies of non-covalent AT + H mixtures lead to a lack of binding for AT and fractionation of H into unbound (separate from AT) or bound material. Gradient elution of ATH from Sepharose-AT gave 2 peaks, a peak containing higher affinity material that had greater anti-factor Xa catalytic activity (708 units/mg heparin) compared with the peak containing lower affinity material (112 units/mg). Sepharose-AT chromatography of the ATH component with short heparin chains (相似文献   

A method to determine the affinity of heparin to thrombin and antithrombin III on equilibrium gel permeation chromatography

Equilibrium gel permeation chromatography was employed to determine the ability of heparin to form complexes with thrombin and antithrombin III. In the eluate from a Sephacryl S-200 column, heparin caused a peak and then a trough in the fluorescence of 48 nM antithrombin III or 63 nM thrombin. The peak-heights with known amounts of heparin were used for standard curves to determine the extent of complex formation by test heparin preparations. Only heparin species with high-affinity for antithrombin III specifically formed a complex with antithrombin III under the conditions used. The ability to form a complex of heparin preparations with different anticoagulant activities for thrombin and antithrombin III could be determined satisfactorily. The heparin species with different affinities for antithrombin III did not coincide those with different affinities for thrombin. Of 4 preparations with one low-affinity and three high-affinity subfractions of heparin for antithrombin III, the species with the lowest affinity for antithrombin III had the highest affinity for thrombin. All of these observations showed that the method could be used to determine the ability to form a complex of test heparin preparations.     

Antithrombin III deficiency: a report of 14 cases belonging to three different kindreds

A hereditary deficiency of AT III is described in 14 subjects belonging to three different kindreds. There is no consanguineity in any of the families investigated. The pattern of inheritance of defect appears autosomal dominant. Seven of the affected subjects presented thrombotic episodes (deep vein thrombosis, splanchnic thrombosis, pulmonary embolization). The main laboratory features were: normal routine clotting tests, decreased AT III activity in all assay systems and concomitantly reduced AT III antigen levels. Crossed immunoelectrophoresis showed only reduced peaks with respect to normal in both plasma and serum. No correlation was found between age of patients and AT III levels.     

A novel matrix for high performance affinity chromatography and its application in the purification of antithrombin III

Viscose fiber, a regenerated cellulose, was evaluated for using as a novel matrix for high performance affinity chromatography. With a one-step activation with epichlorohydrin, heparin can be readily covalently attached to the matrix. This heparin-viscose fiber material was used for purifying antithrombin III (AT III) from human plasma. The purity of the AT III from this one-step purification is 93% as measured by SDS-PAGE and the protein recovery yield is about 90%. This column is highly specific as described by the dissociation constant of the complex of immobilized heparin and AT III, which was 2.83 x 10(-5)mol/L. And more important, this viscose fiber material demonstrated its excellent mechanical property that allows the flow rate to reach up to 900 cm/h or more.     

Behaviour of antithrombin III abnormalities in the crossed immunoelectrophoresis system

Antithrombin III (AT III) abnormalities can be characterized by means of crossed immunoelectrophoresis. In the past, it was thought that the abnormalities could be demonstrated only if heparin is present in the system. Now some conditions (AT III Trento, for example) are known to show an abnormal pattern only in the absence of heparin. This indicates that some of the changes are heparin-independent. Furthermore, it could be demonstrated that in some cases the abnormality is present only in serum (AT III Vicenza, for example). Therefore, the test should be carried out as a screening procedure both in plasma and serum and in the presence or absence of heparin in every case of suspected AT III abnormality.     

Antithrombin III Basel. Identification of a Pro-Leu substitution in a hereditary abnormal antithrombin with impaired heparin cofactor activity

Antithrombin III Basel is a hereditary abnormal antithrombin with normal progressive inhibition activity (normal reactive site) and reduced heparin cofactor activity (impaired heparin binding site). Structures of antithrombin III Basel and normal antithrombin III isolated from the same patient were compared by peptide mapping using the dimethylaminoazobenzene isothiocyanate precolumn derivatization technique. Of the approximately 50 tryptic peptides of normal and abnormal antithrombin III, one peptide comprising residues 40-46 had a different retention time in reversed-phase high performance liquid chromatography. The amino acid sequence of the peptide from antithrombin III Basel had a single substitution of Pro (normal) by Leu (abnormal) at position 41. This substitution is close to an Arg (residue 47) and a Trp (residue 49) which have previously been shown to be critical for heparin binding by antithrombin III. Although additional amino acid substitutions in antithrombin III Basel cannot be ruled out, this Pro-Leu replacement could cause a conformational change by increasing both the helical structure and the hydrophobicity around residue 41. These data suggest that: (i) the heparin binding site of antithrombin III encompasses the region containing residues 41, 47, and 49; and (ii) the impaired heparin cofactor activity of antithrombin III Basel is likely due to a conformational change of the heparin binding site induced by the Pro-Leu substitution at position 41.     

The botanical extracts of Achyrocline satureoides and Ilex paraguariensis prevent methylglyoxal-induced inhibition of plasminogen and antithrombin III

Endogenously produced dicarbonyls, such as methylglyoxal (MG), are involved in advanced glycation end-product formation and thus linked to the pathophysiology of diabetic chronic complications. While the search for synthetic new antiglycation agents continues, little attention has been paid to putative antiglycation agents in natural compounds. Given the link between glycation and oxidation, in this work, we study the effects of methylglyoxal on two model systems; plasminogen and antithrombin III (AT III), then we set out to unravel a possible antiglycation effect for extracts of the flavonoid-rich common herbal species Achyrocline satureoides (AS) and Ilex paraguariensis (IP). Using SAR-PRO-ARG-pNA as a specific thrombin substrate, we show that incubation of plasma with MG decreases heparin activation of AT III by up to a 70%, in a dose-dependent manner. A parallel dose-dependent decrease in plasminogen activity reaching more than 50% was shown using D-BUT-CHT-lys-pNA as a plasmin-specific substrate. Extracts of AS and IP display a dose dependent inhibition of the action of the dicarbonyl, already significant at a 1/100 dilution of the herbal infusions. The inhibition was comparable to that obtained by using millimolar concentrations of known AGE inhibitors such as aminoguanidine and carnosine as well as micromolar concentrations of the antioxidant ascorbic acid. We believe our system of whole plasma glycation over 16 h with micromolar concentrations of MG, coupled with the measurement of activities of plasminogen and AT III by specific substrates provides a straightforward, practical method for monitoring the action of putative antiglycation agents. If predictably milder glycated forms of AT III and plasminogen were to be secreted in vivo, the loss of activities shown here could act synergistically to generate hyperthrombicity.     

Coagulation inhibitors and glycaemic control in non-insulin-dependent diabetes mellitus

The relationship between long-term glycaemic control and the activity of coagulation inhibitors was investigated in 60 non-insulin-dependent diabetes mellitus (NIDDM) patients not on insulin therapy. Overall, the activities of antithrombin III (AT III) (median 96%, range 65–133%), protein C (127%, 24–190%) and protein S (130%, 54–163%) were not reduced. Patients in poor long-term glycaemic control as verified by increased glycated haemoglobin (HbA1c) demonstrated significantly decreased median AT III activity in comparison with patients in good glycaemic control (92% vs 101%,P=0.016). However, individual values for AT III activity were not below the critical limit of 60%. An inverse correlation between AT III activity and long-term glycaemic control (HbA1c) was calculated (r=–0.378,P=0.0029). As AT III concentrations were found to be normal, we propose that non-enzymatic glycation leads to reduced activity of AT III without affecting its concentration.     

Physicochemical characterization of human S-protein and its function in the blood coagulation system.

S-protein, the main inhibitor of the assembly of the membrane attack complex of complement, was isolated from human plasma by a simple purification procedure, which includes barium citrate adsorption, ammonium sulphate precipitation, chromatography on DEAE-Sephacel and Blue Sepharose and gel filtration on Sephacryl S-200. The homogeneous protein (sedimentation coefficient 4.6 S) was obtained in approx. 5% yield relative to its concentration in plasma, which was found to be 0.3-0.5 mg/ml. The final product did not cross-react with antisera against complement proteins or other proteinase inhibitors of human plasma. On polyacrylamide-gel electrophoresis in the presence of sodium dodecyl sulphate, S-protein migrated as a single-chain band with an apparent Mr of 74000 under non-reducing conditions and as a doublet of Mr 78000 and 65000 upon reduction. In plasma or serum S-protein also existed in two forms of corresponding Mr values, as was evidenced by an immunoblot enzyme-linked immunosorbent assay technique. S-protein was found to be an acidic glycoprotein with 10% (W/W) carbohydrate content and several isoelectric points in the range pH 4.75-5.25, and it contained one free thiol group per molecule of protein. The functional properties of S-protein in the complement system were demonstrated by its ability to inhibit complement-dependent cell lysis in a concentration-dependent manner (Ki 0.6 microM) and by its incorporation into the nascent SC5b-7 complex. A new function for S-protein could be revealed in the blood coagulation system. The slow progressive inhibition of thrombin by antithrombin III was not affected by S-protein, whereas the purified protein interfered with the fast inactivation of thrombin clotting as well as amidolytic activity by antithrombin III-heparin complex. The acceleration of this inhibition reaction by heparin was counteracted by S-protein, indicating the ability of S-protein to neutralize heparin activity.