Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Prothrombin”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 505 records · Page 28Linked to original sources
PubMed1987

Electroimmunoassay of prothrombin.

Electroimmunoassay of normal (10-Gla) and Gla-deficient prothrombins containing 0 to 9 Gla (gamma-carboxyglutamyl) residues performed in EDTA against anti- (normal) prothrombin showed that each of the Gla-deficient proteins contained as much antigenic activity as does the normal molecule. In the presence of Ca2+, however, normal prothrombin appeared to show the least while 0- to 2-Gla variants, the most activity. This anomaly arises from the presence of antibodies (Ca-IIAb) which form antigen-antibody (Ag-Ab) complexes when the conformation of the antigen is stabilized in Ca2+. For example, upon fractionation of the antisera and mixing Ca-IIAb (bound to 10-Gla prothrombin, Affi-gel column and eluted by replacing Ca2+ with EDTA) with those reacting with prethrombin1 (non-Gla portion of the molecule), rocket heights in Ca2+ decreased the most with 10- and 9-Gla (32%), followed by 13% with 8-Gla, 2% with 7-Gla and none with 2-Gla prothrombins--indicating that Ca-IIAb do cross react with 7-, 8- and particularly 9-Gla prothrombins. This was also confirmed by the fact that anti 7-Gla but not anti 0-Gla sera contained some antibodies which reacted only in the presence of Ca2+.

Calcium↗
PubMed1993

Prothrombin fragment F1 + 2 concentrations for monitoring anticoagulation therapy with heparin.

We have compared the activated partial thromboplastin time with measurement of prothrombin fragment F1 + 2 concentrations (ELISA assay) during a 24-h period in a group of patients (n = 10) who had undergone elective coronary angioplasty and were anticoagulated post-procedure with heparin 1000 U/h. Four hours after the procedure all the patients were adequately anticoagulated according to activated partial thromboplastin time (median ratio 4.7:1) and the prothrombin fragment F1 + 2 concentration was significantly lower than pre-angioplasty values (0.5 vs 1.4 nmol/l, p = 0.04). At 24 h the median activated partial thromboplastin time ratio was still higher than the pre-procedure value (1.35 vs 0.9, p < 0.01), but the prothrombin fragment F1 + 2 concentration had risen to 2.1 nmol/l, with more variability in individual results within the patient group for the prothrombin fragment F1 + 2 concentration than for activated partial thromboplastin time (interquartile ranges (Q1, Q3) prothrombin fragment F1 + 2, 1.2-2.5; activated partial thromboplastin time, 1.2-1.5). The activated partial thromboplastin time is the standard method of monitoring the anticoagulant effect of heparin but may not fully reflect the functional coagulation status and accurately identify individual patients with less than adequate anticoagulation. Prothrombin fragment F1 + 2 concentrations may provide a more reliable indicator in individual patients of functional coagulation status in certain important situations where anticoagulation is critical such as following complicated coronary angioplasty.

Angioplasty, Balloon, Coronary↗
PubMed1980

Inhibition by warfarin of prothrombin synthesis and of lipid-saccharide synthesis in rat liver.

In vivo and in vitro studies using [3H]glucosamine incorporation into prothrombin and into glycolipids were conducted in rat liver to determine the role of lipid-saccharides in the biosynthesis of prothrombin. In vivo studies demonstrated that 10 mg warfarin/kg inhibited the incorporation of radiolabeled glucosamine into liver prothrombin and glycolipids. This inhibition was similar to the kinetics of inhibition of prothrombin synthesis in the liver. In vitro studies demonstrated a time-dependent increase in the incorporation of radiolabeled glucosamine into lipid-saccharides and prothrombin. This incorporation was inhibited 50% by 5 . 10(-4) M warfarin. Warfarin also inhibited the incorporation of radiolabeled glucosamine into glycolipids in a dose-related manner. In all studies, vitamin K-1 reversed the inhibition of glucosamine incorporation into glycolipids and into prothrombin.

Animals↗
PubMed2006

Isolation and characterization of cotiaractivase, a novel low molecular weight prothrombin activator from the venom of Bothrops cotiara.

In this study, we isolated a novel prothrombin activator from the venom of Bothrops cotiara, a Brazilian lance-headed pit viper (Cotiara, Jararaca preta, Biocotiara), which we have designated "cotiaractivase" (prefix: cotiar- from B. cotiara; suffix: -activase, from prothrombin activating activity). Cotiaractivase was purified using a phenyl-Superose hydrophobic interaction column followed by a Mono-Q anion exchange column. It is a single-chain polypeptide with a molecular weight of 22,931 Da as measured by mass spectroscopy. Cotiaractivase generated active alpha-thrombin from purified human prothrombin in a Ca2+-dependent manner as assessed by S2238 chromogenic substrate assay and SDS-PAGE. Cotiaractivase cleaved prothrombin at positions Arg271-Thr272 and Arg320-Ile321, which are also cleaved by factor Xa. However, the rate of thrombin generation by cotiaractivase was approximately 60-fold less than factor Xa alone and 17 x 10(6)-fold less than the prothrombinase complex. The enzymatic activity of cotiaractivase was inhibited by the chelating agent EDTA, whereas the serine protease inhibitor PMSF had no effect on its activity, suggesting that it is a metalloproteinase. Interestingly, S2238 inhibited cotiaractivase activity non-competitively, suggesting that this toxin contains an exosite that allows it to bind prothrombin independently of its active site. Tandem mass spectrometry and N-terminal sequencing of purified cotiaractivase identified peptides that were identical to regions of the cysteine-rich and disintegrin-like domains of known snake venom metalloproteinases. Cotiaractivase is a unique low molecular weight snake venom prothrombin activator that likely belongs to the metalloproteinase family of proteins.

Amino Acid Sequence↗
PubMed2005

The intriguing world of prothrombin activators from snake venom.

Activation of prothrombin to mature thrombin occurs by the proteolytic action of the prothrombinase complex consisting of a serine proteinase factor Xa, and cofactors factor Va, Ca(2+) ions and phospholipids. Several exogenous prothrombin activators are found in snake venom. They are classified into four groups based on their cofactor requirements. Group A and B prothrombin activators are metalloproteinases whereas group C and D prothrombin activators are serine proteinases. Group C prothrombin activators resemble the mammalian factor Xa-factor Va complex, while Group D activators are structurally and functionally similar to factor Xa. This review provides a detailed description of the current knowledge on all prothrombin activators and highlights several intriguing questions that are yet to be answered.

Animals↗
PubMed1988

A hydrophobic site in human prothrombin present in a calcium-stabilized conformer.

Human prothrombin and prothrombin fragment 1 were demonstrated to bind to Phenyl-TSK columns in the presence of 5.0 mM calcium ions but not in the presence of either magnesium ions or manganese ions. The calcium-dependent interaction of prothrombin fragment 1 is markedly reduced upon oxidation of approximately one mole of tryptophan per mole of protein. The ability of prothrombin fragment 1 to inhibit prothrombin activation by factor Xa in the presence of calcium ions and phospholipid is also markedly reduced by reaction with N-bromosuccinimide. These results provide the first demonstration of a calcium-specific site in prothrombin outside of the "GLA domain".

Binding Sites↗
PubMed1997

Adsorption of bovine prothrombin to spread phospholipid monolayers.

The interaction of bovine prothrombin with phospholipids was measured, using as the lipid source monolayers spread at the air-buffer interface. Fluorescence spectroscopy was implemented to determine the equilibrium concentration of free prothrombin in the aqueous subphase of the protein-monolayer suspensions, in a continuous assay system. The increase in surface pressure (pi) from the protein-monolayer adsorption was also measured and, with values of the adsorbed protein concentration (c[s]), was used to calculate dc(s)/d(pi). At a particular phosphatidylserine (PS) content of liquid-expanded (LE) phosphatidylcholine (PC)/PS monolayers, dc(s)/d(pi) was independent of the initial surface pressure (pi[i]), when this latter value exceeded 30 mN/m. However, dc(s)/d(pi) varied significantly with the relative PS content of the monolayer. Values of the equilibrium dissociation constants calculated from the concentration dependence of delta(pi) indicated that the affinity of prothrombin for LE monolayers was higher at higher PS contents and lower packing densities. The affinity of prothrombin for liquid-condensed (LC) PC/PS monolayers was found to be much weaker relative to LE monolayers of similar phospholipid composition. This approach, employing spread monolayers to study prothrombin-phospholipid binding, coupled with a simple and accurate method to determine the free protein concentration in protein-monolayer suspensions, offers significant advantages for the investigation of protein-membrane interaction. The equilibrium characteristics that describe the interaction of prothrombin with the different phospholipid monolayers under various conditions also provide support for previous results which indicated that hydrophobic interactions are involved in the adsorption of vitamin K-dependent coagulation and anticoagulation proteins to model membrane systems.

Adsorption↗
PubMed2001

Automated detection of the G20210A prothrombin mutation using the LCx microparticle enzyme immunoassay.

BACKGROUND: The prothrombin mutation, a G/A transition at position 20210 in the 3' untranslated region of the prothrombin gene, is associated with an increased risk of deep venous thrombosis and obstetrical complications. Several methods have been developed to detect the mutation; however, given the increased demand for this test in risk factor assessment, the development of simple and efficient screening methods has become necessary. METHODS: We have used a rapid, sensitive, and precise method developed by Abbott Laboratories to detect the prothrombin mutation. The method employs a polymerase chain reaction (PCR) amplification and the Abbot LCx microparticle enzyme immunoassay (MEIA) for detection. This method is able to detect and identify both homozygous and heterozygous genotypes. RESULTS: Two hundred ninety-six patients with a history of deep venous thrombosis, pulmonary embolism, preeclampsia, or cardiovascular disease and 163 control patients were included in this study. The prevalence of the mutation was 5.74% in the high-risk group and 3.06% in the control group. There was complete agreement between the results from the MEIA detection with those obtained using other detection methodologies, namely standard PCR and restriction fragment length polymorphism (RFLP) analysis. CONCLUSIONS: The MEIA detection method of the prothrombin mutation represents a simple, fast, and reliable alternative to standard methods of detection and is well suited for use in routine clinical laboratories. The results of our study confirm others' studies showing a greater incidence of G20210A prothrombin gene mutation in patients with an increased risk of venous thrombosis and pulmonary embolism as well as patients with cardiovascular disease and pregnant women with preeclampsia. It reinforces the necessity of including the screening for prothrombin mutation in populations at risk.

3' Untranslated Regions↗
PubMed2000

Prevalence of factor V Leiden and prothrombin variant G20210A in patients age <50 years with no significant stenoses at angiography three to four weeks after myocardial infarction.

OBJECTIVES: We sought to determine the frequencies of factor V Leiden and prothrombin variant G20210A in patients age <50 years with no significant coronary stenoses three to four weeks after myocardial infarction (MI). BACKGROUND: Factor V Leiden and prothrombin variant G20210A occur frequently in patients with venous thromboembolism. However, the contribution of these mutations to the development of MI requires clarification. METHODS: The frequencies of factor V Leiden and prothrombin variant G20210A were determined in 41 patients age <50 years who had "normal" or "near normal" coronary arteries (no stenosis >50%) at angiography three to four weeks after MI (the study group) and compared with those in 114 patients who had at least one angiographic stenosis >50% after MI (the control group). Patients age > or =50 years with, or without, stenoses were also studied. RESULTS: The frequency of factor V Leiden was 14.6% in patients age <50 years in the study group compared with 3.6% in patients in the control group (odds ratio [OR] 4.7 [95% confidence interval (CI) 1.3-17.7], p = 0.02). The frequency of the prothrombin variant G20210A was 7.3% in the study group compared with 1.8% in the control group (OR 4.4 [95% CI 0.7-27.5], p = 0.12). One or both mutations were present in 8 of the 41 patients (19.5%) age <50 years in the study group compared with 6 of the 114 patients (5.5%) in the control group (OR 4.4 [95% CI 1.4-13.5], p = 0.01). In all 271 patients (irrespective of age) with normal arteries, the frequency of factor V Leiden was 11.7% (7/60) compared with 4.3% (9/211) in patients with at least one >50% stenosis (OR 2.9 [95% CI 1.1-8.3], p = 0.04), and the frequency of prothrombin variant G20210A was 6.7% (4/60) compared with 1.4% (3/211) (OR 4.9 [95% CI 1.1-22.8], p = 0.04), respectively. CONCLUSIONS: The frequencies of factor V Leiden and/or prothrombin variant G20210A are increased in patients age <50 years with normal or near normal coronary arteries after MI.

Aged↗
PubMed2001

G20210A mutation in the prothrombin gene and the risk of recurrent venous thromboembolism.

OBJECTIVES: The study was done to determine whether the G20210A mutation in the prothrombin gene increases the risk of recurrent venous thromboembolism (VTE), both alone and in combination with factor V Leiden. BACKGROUND: Several inherited defects of coagulation are associated with increased risk of first VTE, including a recently identified G20210A mutation in the prothrombin gene. However, whether the presence of this mutation confers an increased risk of recurrent venous thromboembolism is controversial. METHODS: A total of 218 men with incident venous thromboembolism were genotyped for the prothrombin mutation and for factor V Leiden and were followed prospectively for recurrent VTE over a follow-up period of 7.3 years. RESULTS: A total of 29 men (13.3%) suffered recurrent VTE. Five of the 14 carriers of the prothrombin mutation developed recurrent VTE (35.7%; incidence rate = 8.70 per 100 person-years), while 24 of 204 individuals who did not carry the prothrombin mutation developed recurrent VTE (11.8%; incidence rate = 1.76 per 100 person-years). Thus, presence of the G20210A mutation was associated with an approximate fivefold increased risk for recurrent VTE (crude relative risk [RR] 4.93; 95% confidence interval [CI] 1.9-12.9; p = 0.001; age-, smoking-, and body mass index-adjusted RR 5.28; 95% CI 2.0-14.0; p = 0.001). In these data, recurrence rates were similar among those with an isolated mutation in the prothrombin gene (18.2%) as compared to those with an isolated factor V Leiden mutation (19.2%). However, all three study participants who carried both mutations (100%) suffered a recurrent event during follow-up. CONCLUSIONS: In a prospective evaluation of 218 men, the presence ofprothrombin mutation was associated with a significantly increased risk of recurrent VTE, particularly among those who co-inherited factor V Leiden.

Adult↗
PubMed1994

Direct enthalpy measurements of factor X and prothrombin association with small and large unilamellar vesicles.

Isothermal titration calorimetry was used to determine the enthalpy for the calcium-dependent protein conformation change and subsequent interaction of blood clotting factor X and prothrombin with phospholipid vesicles. The effect of vesicle size was also determined. The protein conformation change was accompanied by -12 +/- 1 and -7 to -15 kcal/mol for factor X and prothrombin, respectively. The range of values for prothrombin arose from use of different protein preparations and may be due to non-ideal behavior of this protein when calcium was added. The apparent enthalpy of association (delta H(assoc)) of both factor X and prothrombin with phosphatidylserine (PS)/phosphatidylcholine (PC) large unilamellar vesicles (LUVs, 120 nm diameter) was shown to be near 0 kcal/mol. In comparison, delta H(assoc) for interaction with PS/PC small unilamellar vesicles (SUVs, 40 nm diameter) was -9 +/- 3 and -7 +/- 2 kcal/mol for factor X and prothrombin, respectively. This difference appeared complementary to delta H(assoc) for calcium binding to these vesicles. That is, the interaction of calcium was athermic with SUVs and exothermic with LUVs. While such properties might suggest a considerable difference in the manner of calcium binding to LUVs versus SUVs, little difference in the quantity of calcium bound to SUVs and LUVs was detected by equilibrium dialysis. In any event, the results indicate that protein binding to LUVs was primarily entropy driven whereas binding to SUVs was primarily enthalpy driven. The exothermic process for calcium-dependent factor X or prothrombin binding to SUVs may result from protein-induced changes in the phospholipid packing/calcium interaction, possibly related to changes in how calcium is bound to the phospholipid.

Animals↗
PubMed1982

Vitamin K dependent in vitro production of prothrombin.

During prothrombin biosynthesis, glutamyl residues in prothrombin precursor proteins are carboxylated to gamma-carboxyglutamyl residues by a vitamin K dependent carboxylase. Calcium-dependent and calcium-independent rat prothrombin antibody subpopulations have been produced and utilized to study the liver microsomal precursors of prothrombin that accumulate when vitamin K action is blocked. A substantial portion of the precursor pool accumulating in the vitamin K deficient or warfarin-treated rat will react with a Ca2+-dependent antibody at high calcium concentration and appears to be partially carboxylated. During in vitro incubation in the presence of vitamin K, the fraction of the precursor pool which is tightly bound to the microsomal membrane appears to be the preferred substrate for the vitamin K dependent carboxylation. A small amount of completely carboxylated rather than a large amount of partially carboxylated products are produced during these incubations. Treatment with a Sepharose-bound prothrombin antibody demonstrated that about 20-25% of the total carboxylated microsomal protein precursor pool consists of prothrombin precursors. This treatment removes an equal amount of total carboxylase activity, and the enzyme is active in this carboxylase precursor-antibody complex.

Animals↗
PubMed1984

Characterization of bovine prothrombin mRNA and its translation product.

Prothrombin mRNA has been enriched 20-60-fold by using specific immunoadsorption of bovine liver polysomes. The enriched mRNA was translated in a cell-free protein synthesizing system derived from rabbit reticulocytes, and the radiolabeled translation product was isolated by immunoprecipitation and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The radiolabeled prothrombin synthesized in the cell-free system was then subjected to automated Edman degradation and shown to contain a leader sequence of at least 30 residues that was rich in leucine, phenylalanine, and alanine. In order to fully characterize the leader sequence for prothrombin, a bovine liver cDNA library was constructed containing DNA inserts of over 1000 base pairs. Two cDNA clones coding for bovine prothrombin were isolated from the library and their nucleotide sequences determined. A leader sequence of 43 amino acids was predicted from the sequence of the cDNA, and the first 30 residues were in agreement with the partial sequence obtained by the cell-free protein synthesizing system. From the amino acid sequence of the leader sequence, it is proposed that bovine prothrombin is synthesized with a prepro leader sequence starting with a methionine residue at position -43. The amino acid sequence of the mature prothrombin molecule circulating in plasma was also predicted from the cDNA and shown to be in good agreement with that determined previously by conventional amino acid sequence analysis.

Amino Acid Sequence↗
PubMed1984

Interaction of prothrombin with factor Va-phospholipid complexes.

The effects of factor Va and the phospholipid-binding fragment of factor Va [factor Va light chain (LC), Mr 80000] on the binding of prothrombin, factor X, and factor Xa to phospholipid vesicles are reported. Equilibrium binding experiments were performed that utilized large-volume vesicles, which can be removed from the bulk solution by centrifugation. Factor Va decreased the dissociation constant of the prothrombin-phospholipid complex 50-fold, from 2.0 X 10(-7) M to 4.0 X 10(-9) M. For the factor X-phospholipid complex the decrease was 60-fold (1.8 X 10(-7) M to 3.0 X 10(-9) M) and for factor Xa, 160-fold (1.6 X 10(-7) M to 1.0 X 10(-9) M). The ratios of moles of protein bound to moles of total added factor Va at saturation of phospholipid-bound factor Va indicate an 1:1 stoichiometric complex of either factor Xa, factor X, or prothrombin and phospholipid-bound factor Va. In the presence of factor Va LC, the dissociation constants of factor Xa- and prothrombin-phospholipid complexes were increased, while the maximal protein-binding capacities of the vesicles were not affected by factor Va LC. The data suggest a competitive interaction between factor Xa and factor Va LC binding as well as between prothrombin and factor Va LC binding at the phospholipid surface. From this, it is concluded that the phospholipid-binding fragment of factor Va alone does not serve as the binding site for interactions of factor Xa and prothrombin with factor Va.

Animals↗
PubMed1989

Interaction of clotting factor V heavy chain with prothrombin and prethrombin 1 and role of activated protein C in regulating this interaction: analysis by analytical ultracentrifugation.

Changes in the affinity of the heavy subunit of blood coagulation factor Va (Vh) for prothrombin are thought to be important in regulating the rate of thrombin production. Using analytical ultracentrifugation, we have measured the affinity of bovine Vh for prothrombin and for the prethrombin 1 fragment of prothrombin at 23.3 degrees C, pH 7.65, in 50 mM tris(hydroxymethyl)aminomethane, 0.1 M NaCl, 0.1 mM benzamidine, and either 2 mM Ca2+ or 2 mM ethylenediaminetetraacetate (EDTA). Under these conditions a 1:1 complex of Vh with prothrombin is formed that is governed by a dissociation constant (Kd) of 10 microM, regardless of whether the buffer contains Ca2+ or EDTA. An identical Kd is observed when prethrombin 1 is substituted for prothrombin. This indicates that the fragment 1 portion of prothrombin, containing the gamma-carboxyglutamic acid residues, does not influence the association. Substitution of human prethrombin 1 for the bovine molecule also results in a 1:1 Vh-prethrombin 1 complex governed by a slightly weaker Kd (27 microM). Discrete proteolysis of bovine Vh by the anticoagulant activated protein C converts the Vh to a form with little or no affinity for prethrombin 1 (Kd greater than 1 mM), without detectable change in the mass of the Vh.

Animals↗
PubMed1977

Structure of the prothrombin- and blood clotting factor X-membrane complexes.

The configuration of the prothrombin- and factor X-membrane complexes was investigated by the technique of quasielastic light scattering. It is concluded that the fragment 1 region of prothrombin is located at one end of the prothrombin molecule and that the membrane binding site is at the tip of the fragment 1 region. Prothrombin binds to the surface of the membrane with no detected penetration into the lipophilic region of the membrane. The remainder of the prothrombin molecule extends radially from the membrane surface with maximum protrusion into solution. Factor X also binds to the membrane at one end of the molecule and extends into solution. Based on the evidence presented here and in other communications [Nelsestuen, G. L., and Lim, T. K. (1977), Biochemistry 16, and Nelsestuen, G. L., and Broderius, M. (1977), Biochemistry 16 (respectively the first and second in a series of three papers in this issue)] a model for prothrombin-membrane interaction is given. Quasielastic light scattering appears to be a valuable new method for studying protein-membrane interactions.

Animals↗
PubMed1998

Prothrombin in normal human cerebrospinal fluid originates from the blood.

In spite of the fact that prothrombin is produced by cells within the central nervous system, its presence in the cerebrospinal fluid (CSF) has not been investigated. We determined the concentration of prothrombin in CSF with reference to the concentration in plasma in paired samples from 18 "normal" control patients and 4 patients with relapsing-remitting type of multiple sclerosis (MS). The newly developed ELISA was very specific (no cross-reactivity with thrombin) and sensitive (detection limit--0.7 ng/ml) with an imprecision of CV = 8.3% (intraseries) and 7.0% (interassay). The mean prothrombin concentration in normal CSF was 0.55 mg/l (CV +/- 33%, range: 0.28-0.93 mg/l), in normal plasma 121.8 mg/l +/- 21%, resulting in a mean CSF/plasma concentration quotient (Q(Proth)--4.5 x 10(-3) (CV +/- 35%, range: 2.1-8.3 x 10(-3)) corresponding to a mean albumin quotient in this group of subjects of Q(Alb) = 5.8 x 10(-3). Due to the Q(Proth) and the molecular weight of prothrombin (72 kDa)--similar to that of albumin--we conclude that prothrombin in normal human CSF originates predominantly (>95%) from blood. The enzymatic activity in CSF is conserved. Comparable results obtained in MS patients with only few small MRI lesions suggest that local chronic inflammatory disease of the central nervous system does not influence prothrombin concentration in the CSF if the blood-CSF barrier function is normal.

Biological Transport↗
PubMed2003

Group D prothrombin activators from snake venom are structural homologues of mammalian blood coagulation factor Xa.

Procoagulant venoms of several Australian elapids contain proteinases that specifically activate prothrombin; among these, Group D activators are functionally similar to coagulation factor Xa (FXa). Structural information on this class of prothrombin activators will contribute significantly towards understanding the mechanism of FXa-mediated prothrombin activation. Here we present the purification of Group D prothrombin activators from three Australian snake venoms (Hoplocephalus stephensi, Notechis scutatus scutatus and Notechis ater niger) using a single-step method, and their N-terminal sequences. The N-terminal sequence of the heavy chain of hopsarin D (H. stephensi) revealed that a fully conserved Cys-7 was substituted with a Ser residue. We therefore determined the complete amino acid sequence of hopsarin D. Hopsarin D shows approximately 70% similarity with FXa and approximately 98% similarity with trocarin D, a Group D prothrombin activator from Tropidechis carinatus. It possesses the characteristic Gla domain, two epidermal growth factor-like domains and a serine proteinase domain. All residues important for catalysis are conserved, as are most regions involved in interactions with factor Va and prothrombin. However, there are some structural differences. Unlike FXa, hopsarin D is glycosylated in both its chains: in light-chain residue 52 and heavy-chain residue 45. The glycosylation on the heavy chain is a large carbohydrate moiety adjacent to the active-site pocket. Overall, hopsarin D is structurally and functionally similar to mammalian coagulation FXa.

Amidohydrolases↗