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PubMed1997

Purification and characterization of a variant of human prothrombin: prothrombin Segovia.

A dysprothrombin designated prothrombin Segovia was isolated from the plasma of an individual with normal prothrombin antigen and prothrombin activity lesser than 25% of the control prothrombin activity. Activation by prothrombinase complex showed a lower amidolytic than clotting activity, which suggests a lesser generation of active intermediates than normal prothrombin. When prothrombin Segovia was activated by prothrombinase complex in the absence of factor Va, no thrombin formation was found by functional activities. SDS-PAGE analysis of the molecules derived by activation with prothrombinase complex, Taipan snake venom and Echis carinatus venom showed an accumulation of molecules not cleaved at bond Arg320-Ile321. This was more evident with Echis carinatus venom, which only acts on this bond. Our data suggest that the alteration of prothrombin Segovia impairs the scission of bond Arg320-Ile321.

Blood Coagulation↗
PubMed1975

Purification of an apparent rat liver prothrombin precursor: characterization and comparison to normal rat prothrombin.

Current evidence would suggest that prothrombin is synthesized from a liver precursor molecule in a vitamin K dependent step which involves the attachment of calcium binding groups to the precursor. A protein has now been isolated from the liver of warfarin-treated rats which has the properties predicted for this precursor. The purified precursor is a glycoprotein with a molecular weight indistinguishable from rat prothrombin. Both electrophoretic and isofocusing analyses indicate that the precursor is less negatively charged than prothrombin. Specific proteolysis of the precursor by thrombin, taipan snake venom, or clotting factor Xa yielded fragments indistinguishable from those formed by similar proteolysis of prothrombin. The rate of activation of the precursor to thrombin by factor Xa and Ca-2+ was not stimulated by the addition of phospholipid, while prothrombin activation is greatly stimulated under these conditions. All of the data obtained are consistent with the hypothesis that the protein isolated is a precursor to prothrombin, and that under the influence of vitamin K, this precursor is converted to prothrombin by the addition of a number of acidic calcium binding groups.

Animals↗
PubMed1981

Kinetic and equilibrium metal-ion-binding behaviour reflected in a metal-ion-dependent antigenic determinant in bovine prothrombin. Comparison with bovine prothrombin fragment 1.

Rabbit anti-(bovine prothrombin fragment 1) antibodies were fractionated by using fragment-1 affinity chromatography in the absence of metal ions, and showed an absolute requirement for the presence of metal ions in their interactions with bovine fragment 1 or prothrombin. These antibodies were employed to evaluate both the rate constants for a protein conformation change and the equilibrium metal-ion binding to isolated bovine fragment 1 and intact prothrombin. The close similarity of the rates obtained for the conformation change in fragment 1 and those observed in prothrombin indicated that the same process is involved in both proteins and that the non-fragment-1 region of the prothrombin has essentially no effect on this process in the fragment-1 region. Equilibrium metal-ion-binding studies indicate that the details of the metal-ion-binding process in fragment 1 and prothrombin are essentially the same. We conclude that the metal-ion-binding behaviour of the fragment-1 domain of intact prothrombin is identical with that of isolated fragment 1.

Animals↗
PubMed1986

Prothrombin Segovia: a new congenital abnormality of prothrombin.

A family with a new congenital dysprothrombinemia is presented. The propositus is a 21-yr-old man who presented simultaneously with hemartrosis of the left knee and an extensive hematoma following a minor trauma. Prothrombin time and activated partial thromboplastin time were prolonged. Prothrombin activity was very low when measured by biological assay using physiological activators (7% by one-stage method and 20% by two-stage method) or a Russel's viper venom-cephalin mixture (23%), Notechis scutatus scutatus venom (15%) and Echis carinatus venom (17%); in contrast, the level was found to be borderline to normal using Taipan viper venom (64%) and normal by both staphylocoagulase and immunologic methods. Family studies revealed consanguinity between the propositus' mother and father and both presented a 50% reduced prothrombin level when physiological activators or Echis carinatus viper venom were used. A line of identity between normal and abnormal prothrombin was observed on immunodiffusion. The migration of the abnormal prothrombin was less anodic and was not changed by the addition of calcium. The patient's serum showed 3 bands in the bidimensional immunoelectrophoresis system, whereas normal serum showed only 2 bands. The term prothrombin Segovia is proposed to define this new prothrombin abnormality.

Adult↗
PubMed2000

Prothrombin activation is increased among asymptomatic carriers of the prothrombin G20210A and factor V Arg506Gln mutations.

The risk of venous thrombosis is increased in individuals who carry specific genetic abnormalities in blood coagulation proteins. Among Caucasians, the prothrombin G20210A and factor V Arg506Gln (FV R506Q) mutations are the most prevalent defects identified to date. We evaluated their influence on markers of coagulation activation among participants in the Second Northwick Park Heart Study, which recruited healthy men (aged 50-61 years) from nine general medical practices in England and Wales. They were free of clinical vascular disease and malignancy at the time of recruitment. Genotypes for the two mutations were analyzed using microplate array diagonal gel electrophoresis, and coagulation markers (factor XIIa; activation peptides of factor IX, factor X, and prothrombin; fibrinopeptide A) were measured by immunoassay. Factor VII coagulant activity and factor VIIa levels were determined by a functional clotting assay. Among 1548 men genotyped for both mutations, 28 (1.8%) and 52 (3.4%) were heterozygous for prothrombin G202 IOA and FV R506Q, respectively. The only coagulation marker that was significantly associated with the two mutations was prothrombin activation fragment FI+2 [mean +/- SD, 0.88 +/- 0.32 nmol/L in men with prothrombin G20210A (p = 0.002) and 0.89 +/- 0.30 in men with FV R506Q (p = 0.0001) versus 0.72 +/- 0.24 among non-carriers for either mutationl. This data provides conclusive evidence that heterozygosity for the prothrombin G20210A as well as the FV R506Q mutations in the general population leads to an increased rate of prothrombin activation in vivo.

Blood Coagulation Factors↗
PubMed2003

[Prothrombin deficiency resulted from a homozygous Glu29 to Gly mutation in the prothrombin gene].

OBJECTIVE: To investigate the gene mutations in a pedigree with inherited prothrombin (FII) deficiency. METHODS: The activated partial thromboplastin time (APTT), prothrombin time (PT), FII activity (FII:C) and FII antigen (FII:Ag) test were used for phenotype diagnosis. The genomic DNA was extracted from the peripheral blood of the propositus. All the 14 exons, intron/exon boundaries and the 5' and 3' untranslated regions (UTR) of the prothrombin gene were amplified by polymerase chain reaction (PCR). The PCR products were screened by direct sequencing and the mutations detected were further confirmed by restricted enzyme digestion. One hundred and three healthy blood donors were used as controls. RESULTS: The phenotype of the propositus was prothrombin deficiency (type I). With reference to the prothrombin nucleotide sequence published by Degen & Dacie, three variations were found in the FII gene of the propositus. Among them, the novel mutation was a homozygous A601G subtitution in exon 2. CONCLUSION: The prothrombin deficiency of the propositus is caused by a homozygous Glu29 to Gly mutation in the prothrombin gene.

Blood Coagulation↗
PubMed2005

Molecular genetics of hereditary prothrombin deficiency in Indian patients: identification of a novel Ala362 --> Thr (Prothrombin Vellore 1) mutation.

Prothrombin deficiency is a rare (1:200 000) autosomal recessive disorder caused by diverse mutations in prothrombin gene. We have studied the molecular basis of this disorder in four unrelated Indian patients. The diagnosis was based on prolonged prothrombin (PT) and activated partial thromboplastin times and low factor II coagulant activity (FII: C) measured using a PT based assay. FII: C levels ranged between 4.7% and 17.5%. Mutations were identified in all the four patients. Five different causative mutations including four (80%) missense and an in-frame deletion (20%) were identified. One of them was a novel, Ala362 --> Thr amino acid change affecting 'B' chain of -thrombin. This mutation was present in a compound heterozygous state with a previously reported Arg-1 --> Gln missense change affecting pro-peptide cleavage site. Ala362 --> Thr occurred at a codon, evolutionarily conserved in all the 24 different prothrombins or its related serine proteases studied. Molecular modeling of this mutation was found to cause a conformational change around the region involving a catalytic triad residue His363 and a cysteine residue at codon 364. The FII: C level in this patient was 17.5%. Three other previously reported mutations were also detected in the homozygous state: Arg271 --> Cys in Kringle-2 region, a Glu309 --> Lys in "A" chain of -thrombin and an in-frame deletion of 3 bp (AAG) leading to Del Lys301/302 in "A" chain of -thrombin. This is the first report of the molecular basis of prothrombin deficiency in Indian patients and we suggest the eponym 'Prothrombin Vellore 1' for Ala362 --> Thr mutation.

Adult↗
PubMed1992

Nucleotide sequence of prothrombin gene in abnormal prothrombin-producing hepatocellular carcinoma cell lines.

A protein induced by vitamin K absence or antagonist II, PIVKA-II is synthesized in the liver and possesses a structure similar to prothrombin except that ten glutamic acid residues in amino-terminal Gla domain are not completely gamma-carboxylated and are functionally inactive. This protein can be detected in the plasma of patients with hepatocellular carcinoma (HCC) and used as a new tumor marker. To analyze the mechanism of PIVKA-II production in HCC tissue, the prothrombin gene of PIVKA-II-secreting HCC cell lines was sequenced to detect the mutation in the Gla domain and carboxylase recognition site of leader sequence located on exons I and II that may cause the inhibition of carboxylation. Exons I and II and donor and acceptor site of intron I of the prothrombin gene in two HCC cell lines, PLC/PRF/5 and huH-2, were analyzed by polymerase chain reaction (PCR), and the product was sequenced directly. In addition, RNA samples of these cell lines were used for complementary DNA synthesis, followed by PCR and sequencing. The nucleotide sequences of the Gla domain in both HCC cell lines were conserved. One nucleotide change was detected at nt.554 (adenine to guanine), but this did not influence the amino acid sequence. Splicing sites between exons I and II, the leader sequence of the precursor prothrombin, and protease target sites also were conserved as the reported prothrombin gene, and mutations reported for other des-gamma-carboxy coagulation factors were not detected. These results also were confirmed by DNA analysis of seven human fresh-frozen samples (three PIVKA-II-positive HCC samples and four control specimens). The mechanism of PIVKA-II production in HCC is still unclear, but it is not caused by mutation in the prothrombin gene.

Amino Acid Sequence↗
PubMed1975

The influence of cadmium ions on the adsorption of prothrombin onto A1(OH)3 as a means to purify prothrombin.

1. In the presence of CdSO4(1mM),Al(OH)3(1.3% w/v) completely adsorbs the coagulation factors VII, IX, and X from normal plasma, but factor II (prothrombin) is adsorbed for about 50% only.2. A purification procedure for factor II is developed, using Al(OH)3 adsorption in the presence of Cd2+ as a first step and using column chromatography only once. A 750-fold purification is obtained at a 24% yield. 3. Comparison of the prothrombin thus obtained, with prothrombin isolated by the method of Kisiel and Hanahan (Biochim. Biophys. Acta (1973) 304, 103-113) does not show significant differences in amino acid composition, N-terminal amino acid, molecular weight or immunological properties. 4. Comparison of the two prothrombin preparations in a thrombin-generating system shows that although the final yield of thrombin from a given amount of prothrombin in both preparations is the same, the initial velocity of thrombin formation from our preparation is comparable to that of native prothrombin, whereas the other preparation is converted significantly slower.

Adsorption↗
PubMedDate not supplied

Homologous human blood protein separation using immobilized metal affinity chromatography: protein C separation from prothrombin with application to the separation of factor IX and prothrombin.

Protein C (PC) is a natural anticoagulant and antithrombotic present in human blood at a concentration of 4 microg/mL. Its deficiency can result in excessive clotting and thrombosis. Protein C can be obtained from human blood plasma; however, there are other coagulant proteins in blood, including prothrombin (factor II), which is present in relatively large amounts and is one of the most active components. Protein C and prothrombin are homologous proteins with similar biochemical features; therefore, immunoaffinity chromatography is used for their separation. However, this technology is very expensive, protein C recovery and activity is low, and contamination problems with mouse antibody are likely. Immobilized metal affinity chromatography (IMAC) utilizes the protein metal-binding properties for protein separation. Protein C has twelve surface-accessible histidines, which are the major metal-binding groups for IMAC separation. After investigating metal ion-binding properties of protein C, we used an IDA-Cu column to separate protein C and prothrombin. Following protein adsorption to the column, prothrombin was washed out using a sodium phosphate buffer containing 2 mM imidazole and protein C was recovered with 15 mM imidazole in the buffer. The mild elution condition allows a high protein C activity and a high recovery. Also, this technology introduces no immunoglobulins, and it is relatively inexpensive. IMAC could replace the immunoaffinity technology for the large-scale separation of protein C from blood plasma Cohn Fraction IV-1. In addition, this work demonstrates a significant application of this technology for the separation of factor IX from prothrombin. Prothrombin has proven to be a harmful contaminant in factor IX cocktails that have been administered to humans in the treatment of hemophilia B.

Blood Proteins↗
PubMed1997

Structural features of the kringle domain determine the intracellular degradation of under-gamma-carboxylated prothrombin: studies of chimeric rat/human prothrombin.

Vitamin K antagonists such as warfarin inhibit the vitamin K-dependent gamma-glutamyl carboxylation during protein processing and block the secretion of under-gamma-carboxylated prothrombin (FII) in the rat but not in the human or bovine. Under-gamma-carboxylated prothrombin is also secreted from warfarin-treated human (HepG2) cell cultures but is degraded in the endoplasmic reticulum in warfarin-treated rat (H-35) cell cultures. This differential response to warfarin has been shown to be determined by the structural difference in the proteins rather than by the origin of the cell line. When recombinant rat prothrombin (rFII) and human prothrombin (hFII) were expressed in a transformed human kidney cell line (HEK293), secretion of rFII but not hFII was drastically decreased in response to warfarin. To determine the structural signal required for this differential response, chimeric cDNAs with the propeptide/Gla domains, kringle domain, and serine protease domain exchanged between rFII and hFII were generated (FIIRHH and FIIHRR, FIIRRH and FIIHHR, FIIRHR and FIIHRH) and expressed in both warfarin-treated HEK293 cells and HepG2 cells. The presence of the hFII kringle domain changed the stability of rFII to that of hFII, and the rFII kringle domain changed the stability of hFII to that of rFII. The kringle domain therefore is critical in determining the metabolic fate of under-gamma-carboxylated prothrombin precursors during processing. Prothrombin contains two kringle structures, and expression of additional rFII/hFII chimeras (FIIHrhH and FIIHhrH, FIIRrhR, and FIIRhrR) was used to determine that the first of the two kringles plays a more important role in the recognition process.

Animals↗
PubMed1987

Prothrombin Poissy: a new variant of human prothrombin.

A new congenital dysprothrombinaemia is described in a newborn baby girl who presented severe bleeding from the second day of life. Routine coagulation tests showed very prolonged prothrombin time and activated partial thromboplastin time with about 2% prothrombin activity in a one-stage assay. Staphylocoagulase and Echis carinatus venom prothrombin assays were respectively 35% and 25%. The prothrombin antigen level was 47% and its migration in crossed immuno-electrophoresis was abnormal. Family study revealed the presence of both normal and abnormal prothrombin in the plasma of three family members: the father, the mother and the brother. Thrombin generation in a system free from natural inhibitors showed that the abnormal prothrombin was slowly and incompletely activated. The propositus is thought to be homozygous for a 'lazy' dysprothrombin.

Blood Coagulation Disorders↗
PubMed1992

Prothrombin Himi: a compound heterozygote for two dysfunctional prothrombin molecules (Met-337-->Thr and Arg-388-->His).

A congenitally dysfunctional form of prothrombin, Prothrombin Himi, shows reduced fibrinogen clotting activity, although it retains full hydrolytic activity toward synthetic substrates. To elucidate the structural abnormality of the variant prothrombin, we first performed genetic analysis of dysprothrombin. Polymerase chain reaction amplification of the exons 8 through 14 of the proband and her family members' prothrombin genes, which code the thrombin moiety, followed by single-strand conformation polymorphism analysis, identified two variant conformers in exon 10 specific to this family. One variant allele detected in the father was inherited by the proband and one of her sisters, and the other detected in the mother was also inherited by them. This result indicates that the proband has two different base pair changes in the gene. Sequencing showed two novel point mutations in the proband's gene. One is a T to C transition at position 8751, resulting in the substitution of threonine for methionine at codon 337 (Thrombin Himi I). The other is a G to A transition at 8904, resulting in the substitution of histidine for arginine at codon 388 (Thrombin Himi II). By sequencing analysis of her parents, it was determined that Thrombin Himi I was inherited from the father and Thrombin Himi II from the mother. These results confirm that Prothrombin Himi is compound heterozygous for two dysfunctional prothrombin molecules.

Amino Acid Sequence↗
PubMed1993

In vitro evaluation of factor VIII--bypassing activity of activated prothrombin complex concentrate, prothrombin complex concentrate, and factor VIIa in the plasma of patients with factor VIII inhibitors: thrombin generation test in the presence of collagen-activated platelets.

Clinical efficacy of plasma-derived products with factor VIII--bypassing activity in patients with factor VIII inhibitors is difficult to evaluate. It is also difficult to predict efficacy by coagulation assay. A test of thrombin generation in defibrinated plasma and in the presence of activated platelets was used to test the bypassing activity of the most currently used products (activated prothrombin complex concentrate from various origins, prothrombin complex concentrate, and factor VIIa). The bypassing activity was evaluated in the absence and presence of tissue factor. In plasma with inhibitor, activated prothrombin complex concentrate elicited dose-dependent thrombin formation, whereas prothrombin complex concentrate and factor VIIa induced only minimal thrombin activity. Addition of tissue factor in the assay elicited thrombin generation in the presence of factor VIIa and prothrombin complex concentrate and allowed additional thrombin formation in the presence of activated prothrombin complex concentrate. Although it is hazardous to extend results of in vitro testing to clinical efficacy, our study sheds some light on the mechanism of action of the various substances used to treat bleeding episodes in patients with factor VIII inhibitors.

Blood Coagulation Factors↗
PubMed1976

Effect of polylysine on the activation of prothrombin. Polylysine substitutes for calcium ions and factor V in the factor Xa catalyzed activation of prothrombin.

Polylysine has been demonstrated to dramatically accelerate the rate of the factor Xa catalyzed activation of both prothrombin and prethrombin 1. Under the present experimental conditions (pH 8.0, 23 C), no detectable activation of prothrombin or prethrombin 1 occurs with either factor Xa or polylysine alone. The activation of prethrombin 2, the direct precursor of alpha-thrombin, by factor Xa is not stimulated by polylysine. The activation of either prothrombin or prethrombin 1 by factor Xa in the presence of polylysine is partially inhibited by the presence of 5 mM CaCl2. Electrophoretic analysis in sodium dodecyl sulfate showed that the products that were formed in the above activation system comigrated with the reaction products derived from prothrombin activated by factor Xa in the presence of calcium ions and phospholipid. It is suggested that polylysine stimulates the factor Xa-catalyzes activation of prothrombin by replacing the combination of calcium ions and factor V.

Animals↗
PubMed2001

The use of prothrombin(S525C) labeled with fluorescein to directly study the inhibition of prothrombinase by antithrombin during prothrombin activation.

Serine 525 of human prothrombin was mutated to cysteine and covalently labeled with fluorescein to make II(S525C)-fluorescein. Kinetics of cleavage of this derivative by prothrombinase are identical to those of wild-type prothrombin. Cleavage is coincident with a 50% increase in fluorescence intensity and the product is catalytically inactive. Thus, it allows convenient monitoring of prothrombin activation without generating active thrombin. The kinetics of inhibition of factor Xa (FXa) by antithrombin (AT) and AT-heparin were measured by monitoring activation of II(S525C)-fluorescein and the hydrolysis of the chromogenic substrate S2222 in the presence of AT. With S2222 as the substrate the rate constant for inhibition of FXa, Ca(2+), and unilamellar vesicles of phosphatidylcholine and phosphatidylserine (75:25) (PCPS) vesicles by AT was 3.51 x 10(3) m(-1) s(-1); when factor Va (FVa) was included the rate constant was 1.55 x 10(3) m(-1) s(-1). In the absence of FVa, II(S525C)-fluorescein had no effect on inhibition. When II(S525C)-fluorescein was the substrate, however, FVa at saturating concentrations profoundly protected FXa from inhibition by AT, increasing the half-life from 3 min with FXa, Ca(2+), PCPS, and II(S525C)-fluorescein, to greater than 69 min when FVa was included. Thus, both FVa and prothrombin are necessary for this level of protection. In the absence of prothrombin, FVa decreased the second order rate constant for inhibition by the AT-heparin complex from 1.58 x 10(7) m(-1) s(-1), for FXa, Ca(2+), and PCPS, to 7.72 x 10(6) m(-1) s(-1). II(S525C)-fluorescein and factor Va together reduced the rate constant to less than 1% of that for FXa, Ca(2+), and PCPS. At a heparin concentration of 0.2 unit/ml, this corresponds to a half-life increase from 1 s to 136 s.

Antithrombins↗
PubMed1999

The relationship of mutations in the MTHFR, prothrombin, and PAI-1 genes to plasma levels of homocysteine, prothrombin, and PAI-1 in children and adults.

Studies in adults have demonstrated that the genetic mutations C677T methylenetetrahydrofolate reductase (MTHFR), prothrombin 20210A, and the 4G polymorphism of the plasminogen activator inhibitor-1 (PAI-1) gene are associated with elevated plasma levels of homocysteine. prothrombin and PAI-1, respectively and with an increased risk of thrombosis. No similar data is available in children. Therefore, we assessed the relationship of plasma levels of homocysteine, prothrombin and PAI-1 with their respective mutations in 197 normal children, compared to 40 adults. By stepwise multiple regression, homocysteine was positively associated with age, PAI-1 activity was negatively associated with age, while PAI-1 antigen and prothrombin levels were associated with gender, being higher in girls than boys. When the genotypes were added to the regression model as additional explanatory variables, the MTHFR genotype accounted for 2.9% of the variance of homocysteine (p = 0.024), and the PAI-1 gene accounted for 2.7% of the variance of PAI-1 antigen levels (p = 0.023). Of children homozygous for the MTHFR mutation, 35% had homocysteine levels > or = the age-specific 95th percentile, compared to 2% heterozygotes and 5% wild type normals (p = 0.0001). The mean homocysteine level was higher in children homozygous for the MTHFR gene (8.4 micromol/1) than in heterozygotes (5.5 micromol/l), p <0.05. Of children homozygous for the 4G polymorphism of the PAI-1 gene, 19% had PAI-1 activity levels > or = the age-specific 95th percentile, compared to 2% of heterozygotes and 3% of wild type normals (p = 0.003). Studies of the incidence of the MTHFR, prothrombin, and PAI-1 4G/5G genotypes in children with thrombosis, when compared to these healthy normals, will provide evidence as to which of these genes are associated with thrombophilia.

Adolescent↗
PubMed1985

Tb3+ binding to bovine prothrombin and bovine prothrombin fragment 1.

The binding of Tb3+ to bovine prothrombin and the amino-terminal 156 residues of prothrombin (F-1) was studied. On the basis of various Tb3+ emission properties, three classes of Tb3+-binding sites were described. The first class contained three high affinity sites in the F-1 region. These sites were filled noncooperatively and were saturated with Tb3+ before the other classes of sites started to fill. Ho3+ quenching of Tb3+ emission showed that these sites were in close proximity to one another (estimated distances 6-12 A). The second class of sites contained three lower affinity sites, also in the F-1 region. These sites bound Tb3+ in a stoichiometric manner and saturated prior to metal binding to the final class of sites. The number of protein ligands binding Tb3+ in the high affinity sites decreased as this second set of sites was filled. Ho3+ quenching of Tb3+ emission suggested that these sites were closely spaced and/or close to the first set of sites. The third class of sites contained 4-6 low affinity sites unique to prothrombin (not in the F-1 region). These sites were not studied extensively, but Tb3+ did not appear to bind stoichiometrically and did not saturate these sites in a manner similar to the other two classes of sites. The emission properties of Tb3+ bound to F-1 were different in KCl versus NaCl containing buffer while the emission properties of Tb3+ bound to prothrombin were not. Optimum conditions for studying lanthanide binding to F-1 (i.e. when Tb3+ bound to F-1 showed emission properties similar to Tb3+ bound to prothrombin) were when F-1 experiments were done at low F-1 concentrations in buffer containing 0.1 M KCl.

Animals↗