Fucosylated chondroitin sulfate as a new oral antithrombotic agent

Fucosylated chondroitin sulfate is a potent anticoagulant polysaccharide extracted from sea cucumber. Its anticoagulant activity is attributed to the presence of sulfated fucose branches. We have shown that intravascular injection of fucosylated chondroitin sulfate inhibits thrombus formation in a venous and an arterial shunt model in rats. Since this compound resists digestion by enzymes that cleave mammalian glycosaminoglycans, we investigated the possibility that fucosylated chondroitin sulfate might be absorbed after oral administration. In fact, after oral administration of fucosylated chondroitin sulfate to rats, we observed a dose-dependent increase in the plasma anticoagulant activity, as assessed by assays for activated partial thromboplastin time (aPTT) and thrombin time (TT) (about 3- and 5-fold, respectively) and by anti-IIa activity. Furthermore, animals receiving daily oral doses of this glycosaminoglycan showed a decrease in thrombus weight on experimental models of venous and arterial shunt thrombosis. This antithrombotic action clearly has a strong relationship with anticoagulant activity. Similar doses of heparin administered orally had no effect on the plasma anticoagulant activity or on the thrombus weight. Finally, we observed that fucosylated chondroitin sulfate given orally to rats did not modify the bleeding time. Overall, our results indicate that fucosylated chondroitin sulfate is absorbed after oral administration and could become a promising oral anticoagulant.

[A component of earthworm fibrinolytic enzyme having higher thrombolytic activity than total components in vivo]

AIM

To select higher thrombolytic and lower toxic single component of earthworm fibrinolytic enzymes (EFE).

METHODS

EFE containing total components were obtained by affinity chromatography from Eisenia fetida. Using ion-exchange chromatography to separate three main components EfP-0-2, EfP-I-1 and EfP-I-2 from EFE, their thrombolytic activity and toxicity were compared with EFE.

RESULTS

Among these components, EfP-I-1 had higher thrombolytic activity in vitro. When 4.5 mg x kg(-1) of these components were injected, the contents of fibrinogen in rat serum were not affected, but only EfP-I-1 exhibited distinct thrombolytic activity. When 6.0 mg x kg(-1) of them were injected intravenously, the bleeding time was not evidently delayed only by EfP-I-1. The acute toxicity test showed that the LD50 of EfP-I-1 was higher than EFE by 2. 17 times.

CONCLUSION

Because of distinct thrombolytic activity, lower toxicity in vivo, higher content in EFE and easy to purify, EfP-I-1 was adapted to be developed as a single component medicine for treating thrombus.

[Purification and activity calculated of fibrinolyric factors from Eupolyphaga sinensis]

Three kinds ( EFF-1, EFF-2 and EFF-3) of fibrinolytic factor were separated by ammonium sulphate precipitation, DEAE-cellulose and preparative PAGE electrophoresis from female Eupolyphaga sinensis Walker. Their molecular weights were proved to be 41kd, 32.9 kd and 30.6 kd respectively with SDS-PAGE electophoresis. Their Activities as plasminogen activator were 171.3 U/mg, 234.0 U/mg and 148.5 U/mg. In addition, EFF-2 and EFF-3 were not only fibrinolytic activities but also have plasminogen activator on fibrinous plate lacked of plasminogen . There had been no such components of plasminogen activator and fiberinolytic enzyme from Eupolyphaga sinensis reported yet.

[Purification and biochemical character of a fibrinolytic protein from Eupolyphaga sinensis]

A novel of fibrinolytic protein has been separated and purified by ammonium sulfate fractionation, DEAE-cellulose and SephadexG-75 Column chromatography from the tissue of the female Eupolyphaga sinensis in the paper. The protein showed an apparent molecular weight of 41.3 kD on sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis. In addition, it includes 10.5% sugar. Its specific activity to hydrolyze fibrin was 547.86 u/mg. The enzyme activity was inhibited by Mg2+, Ca2+, protein inhibitors, such as 8mol/L urea and 1% beta-mercaptoethanol, and serine protease inhibitor such as phenylmethanesulfonyl fluoride (PMSF), but wasn't inhibited by Na+, K+ and ethylenediaminotetraacetic acid (EDTA). The protein was stable under 40 degrees C and it's optimal temperature was also 40 degrees C. It's optimal pH was 8.0. It showed a different way between the activity and UK when they degrade the plasminogen. Based on all the messages the protein can be suggested to be a novel fibrinolytic protein. There have been no such component of fiberinolytic enzyme from Eupolyphaga sinensis walker reported yet.

Process scale-up studies for protein C separation using IMAC

Protein C (PC) is the pivotal anticoagulant and antithrombotic in the human coagulation cascade. PC deficiency can disturb the blood hemostasis and cause thrombosis, inhibiting oxygen transport to tissue, and resulting in major medical problems such as deep vein thrombosis (DVT). The current treatment can cause bleeding and other major medical problems. PC circulates in the blood as a zymogen and is only activated when and where it is needed. PC is a safe anticoagulant without harmful side effects. A combination of ion-exchange chromatography and IMAC IDA-Cu was studied for the relatively large scaled PC separation from Cohn fraction IV-1. Almost half of the active PC was recovered by using this process. In future work, we will verify the linearity of the IMAC column scale-up. This process can be used to produce PC from Cohn fraction IV-1 at large quantities and low cost to treat PC-deficient patients.

[Study on antithrombotic fraction of Herba Siegesbeckiae]

OBJECTIVE

To analyze the compounds of antithrombotic fraction of Herba Siegesbeckiae.

METHODS

The compound type and the content of kirenol of antithrombotic fraction were analyzed by LC/MS and HPLC.

RESULTS

In the antithrombotic fraction, the compound type was diterpenoids, and the content of kirenol more than 10 percent.

CONCLUSION

Diterpenoids were main compounds in the antithrombotic fraction of Herba Siegesbeckiae.

Antithrombotic Activities of Aqueous Extract from Radix Ophiopogon japonicus and Its Two Constituents

To provide further pharmacological evidence for its clinical use in thrombotic diseases, the antithrombotic activities of the aqueous extract of Radix Ophiopogon japonicus (ROJ-ext) were studied in mouse and rat models. The results showed that ROJ-ext remarkably decreased length of tail thrombus in mice at 48 h and 72 h after carrageenan injection at doses of 12.5 and 25.0 mg/kg. Meanwhile, ROJ-ext markedly inhibited thrombosis induced by arterial-venous (AV) shunt (silk thread) in rats at doses of 6.25 and 12.5 mg/kg. Furthermore, ROJ-ext and one of its components, ruscogenin, significantly inhibited platelet aggregation induced by adenosine diphosphate (ADP) in rats by oral administration of 12.5 mg/kg or 0.7 mg/kg for three times, however, ophiopogonin D 1.4 mg/kg only showed slight inhibition. On the other hand, ophiopogonin D (0.5-2.0 mg/kg, p.o.) and ruscogenin (0.25-1.00 mg/kg, p.o.) produced dose-related inhibition of venous thrombosis induced by tight ligation of the inferior vena cava for 6 h in mice by once oral administration. The findings of this study indicate that an aqueous extract of Radix Ophiopogon japonicus (ROJ-ext) exerted significant antithrombotic activity and ruscogenin and ophiopogonin D are two of its active components, which supported its therapeutic use for thrombotic diseases.

Enzymological characterization of FII(a), a fibrinolytic enzyme from Agkistrodon acutus venom

AIM

To study the enzymological characterization of a fibrinolytic enzyme (FII(a)) from Agkistrodon acutus venom.

METHODS

The fibrinogenolytic effect and the influences of several protease inhibitors, chelating agents, and metal ions on fibrinogenolytic activity were visualized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The metal content of FII(a) was determined by atomic absorption spectroscopy.

RESULTS

After incubation with FII(a) (0.25 g/L), Aalpha-, Bbeta- and gamma-chains of fibrinogen disappeared within 5 min, 30 min, and 8 h , respectively. The molecular weights of major degradation products were 45,000 and 41,000, which were different from those bands produced by plasmin. The fibrinogenolytic activity of FIIa was strongly inhibited by ethylenediamine tetraacetic acid (EDTA), ethyleneglycol tetraacetic acid (EGTA), dithiothreitol and cysteine, but not by phenylmethyl-sulfonyl fluoride and soybean trypsin inhibitor. Zinc (3171+/-25 mg/kg), potassium (489+/-17 mg/kg) and calcium (319+/-13 mg/kg) were found in FIIa. Zn2+, Ca2+ and Mg2+ could recover the fibrinogenolytic activity of FIIa, which was inhibited by EDTA. Only Ca2+ could recover the fibrinogenolytic activity inhibited by EGTA.

CONCLUSION

FIIa can degrade the Aalpha-, Bbeta- and gamma-chains of fibrinogen. FII(a) is a metalloproteinase, and Zn2+, Ca2+, and disulfide bonds are necessary for its fibrinogenolytic activity.

Cloning and expression of earthworm fibrinolytic enzyme PM(246) in Pichia pastoris

We have cloned, expressed, and purified a novel earthworm fibrinolytic enzyme (EFE) of Lumbricus rubellus in Pichia pastoris. Its cDNA sequence revealed a 747bp region containing an intact ORF that encodes a protein of 246 amino acid residues, designated as EFE PM(246). While EFE PM(246) is distinct, its cDNA shows a high degree of sequence homologies with four other EFE cDNAs registered in GenBank. The recombinant EFE PM(246) was active, showing a fibrinolytic activity of 7.5 x 10(6)U/L in basal salts medium, a higher fibrinolytic activity than those produced in other expression systems. The recombinant EFE PM(246) expressed in basal salts medium was purified by a three-step purification procedure with a recovery rate of about 20%. This is the first report detailing the successful purification of a genetically engineered earthworm fibrinolytic enzyme. The main physiochemical features of the EFE PM(246), including temperature stability, pH resistance, and sensitivity to some protein inhibitors, were also characterized.

Purification and characterization of fibrinolytic enzyme from cultured mycelia of Armillaria mellea

A fibrinolytic enzyme was purified from the cultured mycelia of Armillaria mellea by ion-exchange chromatography followed by gel filtration, and was designated A. mellea metalloprotease (AMMP). The purification protocol resulted in a 627-fold purification of the enzyme, with a final yield of 6.05%. The apparent molecular mass of the purified enzyme was estimated to be 21kDa by SDS-PAGE, fibrin-zymography and gel filtration chromatography, which revealed a monomeric form of the enzyme. The optimal reaction pH value and temperature were, pH 6.0, and 33 degrees C, respectively. This protease effectively hydrolyzed fibrinogen, preferentially digesting the Aalpha-chain over the Bbeta- and r-chains. Enzyme activity was inhibited by Cu(2+) and Co(2+), but enhanced by the addition of Ca(2+) and Mg(2+) ions. Furthermore, AMMP activity was potently inhibited by EDTA, and was found to exhibit a higher specificity for the substrate S-2586 for chymotrypsin, indicating that the enzyme is a chymotrypsin-like metalloprotease. The first 24 amino acid residues of the N-terminal sequence were MFSLSSRFFLYTLCL SAVAVSAAP, which is extremely similar to the 24 amino acid residues of the N-terminal sequence of the fruiting body of A. mellea. These data suggest that the fibrinolytic enzyme AMMP, obtained from the A. mellea exhibits a profound fibrinolytic activity. The mycelia of A. mellea may thus represent a potential source of new therapeutic agents to treat thrombosis.

Crystal structure of a non-hemorrhagic fibrin(ogen)olytic metalloproteinase complexed with a novel natural tri-peptide inhibitor from venom of Agkistrodon acutus

Thrombotic occlusive diseases pose a great threat to human health. Thrombolytic agents are in widespread use for the dissolution of arterial and venous pathologic thrombi in these kinds of diseases. Snake venom metalloproteinases (SVMPs) can act directly on fibrin/fibrinogen and are therefore potential candidates for therapeutic use against thrombotic occlusive diseases. In this study, we have determined the crystal structure of FII, a novel non-hemorrhagic SVMP isolated from Anhui Agkistrodon acutus snake venom by molecular replacement. The structure reveals that FII is a member of the P-I class SVMPs. The Zn2+ ion essential for hydrolytic activity is found in the active site and is tetrahedrally co-ordinated by three histidine residues and water molecule. Unambiguous electron density for a tri-peptide with sequence KNL is also found located near the active site. Biochemical evidences show that the tri-peptide KNL can inhibit the enzymatic activity of FII.

Honokiol inhibits arterial thrombosis through endothelial cell protection and stimulation of prostacyclin

AIM

To study the effect of honokiol on arterial thrombosis and endothelial cells.

METHODS

Rabbit platelet aggregation was performed with Borns turbid method. Thrombosis was produced by the endothelial injury stimulated with electric current. Rat aortic endothelial cells (RAEC) were cultured and cell viability was assessed using the MTT assay. Nitric oxide (NO) concentrations in serum-free media of RAEC were determined using the kinetic cadmium-reduction method. The stable metabolite prostacyclin was measured in serum-free media of RAEC by radioimmunoassay.

RESULTS

Honokiol (37.6-376 micromol/L) decreased rabbit platelet aggregation in vitro in a concentration-dependent manner, while intravenously injection of honokiol (0.12-12 microg/kg) significantly inhibited rabbit platelet aggregation induced by collagen ex vivo. In the electrical current-stimulated carotid thrombosis model in rats, honokiol (5-50 microg/kg, iv) prolonged the thrombus occlusion time in a does-dependent manner. In vitro honokiol (0.376-37.6 micromol/L) effectively protected cultured RAEC against oxidized low density lipoprotein (ox-LDL) injury, and significantly increased 6-keto-PGF1alpha (the stable metabolite of prostacyclin) in serum-free media of RAEC. Honokiol also increased NO level in RAEC serum-free medium at a lower concentration range (0.0376-0.376 micromol/L), but honokiol 3.76 micromol/L decreased NO level.

CONCLUSION

Honokiol is a potent arterial thrombosis inhibitor. Endothelial cell protection and the stimulation of prostacyclin release may be its main anti-thrombosis mechanism. Stimulation of NO release in endothelial cells may play a role, but it is not a key factor.

Fibrin(ogen)olytic character of FIIa isolated from Agkistrodon acutus venom

AIM

To investigate the fibrin(ogen)olytic character of FIIa isolated from Agkistrodon acutus venom in vitro and in vivo.

METHODS

125I-labeled human plasma clot lysis was measured in vitro and rabbit carotid artery thrombosis was as an in vivo model.

RESULTS

In vitro, urokinase (UK) at 25, 35, 40, 45, 60 kU/L and FIIa at 0.08, 0.23, 0.4, 0.5, and 0.7 g/L resulted an equivalent clot lysis (20%, 40%, 50%, 60%, and 80%). UK at 25 to approximately 60 kU/L induced 27.3%+/-3.6%, 35.2%+/-2.3%, 39.3%+/-2.4%, 44.2%+/-4.6%, and 51.1%+/-1.2% fibrinogen degradation. But FIIa at 0.08 approximately -0.7 g/L induced 95.4%+/-0.3%, >95.6%, >95.6%, >95.6%, >95.6% fibrinogen degradation respectively. In vivo, UK 40 kU/kg and FIIa 1.0 mg/kg reduced the weight of residual thrombus to 9.0+/-2.5 mg and 7.8+/-3.5 mg compared with negative control group (30.0+/-5.4 mg). But the fibrinogen degradation rate after UK 40 kU/kg and FIIa 1.0 mg/kg treatment was 24.4%+/-6.2% and 4.1%+/-7.8%, respectively (P<0.05, n=6). The order of the lysis speed after UK 125 kU/L treatment was platelet poor plasma (PPP) clots>the whole blood clots>platelet rich plasma (PRP) clots. The sequence for FIIa 0.4 g/L was PRP >PPP >whole blood clots.

CONCLUSION

At the same percentage of clot lysis, FIIa degraded more fibrinogen than UK did in vitro but less fibrinogen than UK did in vivo. The order of the lysis speed was PPP>whole blood clots>PRP clots for UK and PRP>PPP>whole blood clots for FIIa.

The anticoagulant fraction from the leaves ofDiospyros kaki L. has an antithrombotic activity

The leaves of Persimmon (Diospyros kaki L.) has long been used for tea in Korea since it was thought to be effective against hypertension. An anticoagulant fraction was purified through gel filtration G-100, hydrophobic, gel filtration G-150, and FPLC, Phenyl superpose column chromatographies. The purified fraction was homogenous and its Mr was estimated 10,000 Da by gel filtration and SDS-PAGE. The purified fraction was sensitive to treatment of subtilisin B, but not to heat and its activity was not changed after periodate oxidation, indicating that the activity was not due to carbohydrates. It delayed thrombin time (TT), activated partial thromboplastin time (APTT), and prothrombin time (PT) using human plasma. TT was more sensitive than APTT and PT, suggesting that the anticoagulant activity may be caused by a degradation or a defect of fibrin or thrombin. It did not cause the hydrolysis of fibrin after incubation. However, it inhibited thrombin-catalyzed fibrin formation with a competitive inhibition pattern. These results indicate that it may be an antithrombotic agent and that it is bound to fibrinogen binding sites of thrombin.

Direct-acting fibrinolytic enzymes in shark cartilage extract: potential therapeutic role in vascular disorders

Fibrinogen and fibrin are molecules with overlapping roles in blood clotting, fibrinolysis, wound healing, inflammation, matrix and cellular interactions and neoplasia. There is currently much interest in the possible use of fibrinolytic agents in human therapeutics. In this study, we report the presence of fibrinolytic activities in shark cartilage extract (SCE). In vitro, SCE at 100 microg/ml completely degraded fibrin gel in an aprotinin-insensitive manner, suggesting a non-plasmin molecular nature. SCE was able to cleave all chains of fibrinogen and fibrin and the cleavage was completely inhibited by 1,10-phenanthroline, suggesting an essential role for metalloprotease(s) in this process. Using fibrinogen zymography, we show that SCE contains two plasmin-independent fibrinolytic activities and that these activities are correlated with the presence of 58 and 62 kDa proteases in the extract. SCE-fibrinolytic activities are inhibited by dithiothreitol, suggesting that disulfide bonds are necessary for the protease structure. Finally, using thromboelastography, SCE markedly induced retraction of human platelet-rich plasma (PRP) clot, this process being completely abolished by 1,10-phenanthroline. These data suggest the presence of novel non-plasmin fibrinolytic activities within SCE. This extract may thus represent a potential source of new therapeutic molecules to prevent and treat vaso-occlusive and thromboembolic disorders.

Dermatan sulfate is the predominant antithrombotic glycosaminoglycan in vessel walls: implications for a possible physiological function of heparin cofactor II

The role of different glycosaminoglycan species from the vessel walls as physiological antithrombotic agents remains controversial. To further investigate this aspect we extracted glycosaminoglycans from human thoracic aorta and saphenous vein. The different species were highly purified and their anticoagulant and antithrombotic activities tested by in vitro and in vivo assays. We observed that dermatan sulfate is the major anticoagulant and antithrombotic among the vessel wall glycosaminoglycans while the bulk of heparan sulfate is a poorly sulfated glycosaminoglycan, devoid of anticoagulant and antithrombotic activities. Minor amounts of particular a heparan sulfate (< 5% of the total arterial glycosaminoglycans) with high anticoagulant activity were also observed, as assessed by its retention on an antithrombin-affinity column. Possibly, this anticoagulant heparan sulfate originates from the endothelial cells and may exert a significant physiological role due to its location in the interface between the vessel wall and the blood. In view of these results we discuss a possible balance between the two glycosaminoglycan-dependent anticoagulant pathways present in the vascular wall. One is based on antithrombin activation by the heparan sulfate expressed by the endothelial cells. The other, which may assume special relevance after vascular endothelial injury, is based on heparin cofactor II activation by the dermatan sulfate proteoglycans synthesized by cells from the subendothelial layer.

Discovery and Pre-clinical Development of Antithrombotics from Hematophagous Invertebrates

Bloodfeeding (hematophagous) parasites have evolved effective means of inhibiting mammalian thrombosis, thereby facilitating the acquisition and digestion of a bloodmeal. To date, specific inhibitors of coagulation and platelet function have been identified from numerous invertebrate species, representing an impressive array of convergent functional strategies. These parasite antithrombotics, in addition to playing a critical role in the diseases caused or transmitted by bloodfeeding invertebrates, may also serve as potentially useful therapeutic agents for the treatment of a variety of conditions associated with activation of thrombosis. A number of naturally occurring anticoagulants and platelet inhibitors have been evaluated in vivo, with some currently in varying stages of preclinical and clinical development. Because of the unique specificity and potency of parasite antithrombotics, these invertebrate natural products hold great promise for improving the treatment of a variety of human illnesses, including heart disease, stroke, and cancer.

[Preliminary studies on in vitro and in vivo thrombolytic activities of thrombolytic enzyme from an induced Bacillus subtilis strain]

OBJECTIVE

To separate and purify a novel thrombolytic enzyme (FSC2-13) from culture media of an induced Bacillus subtilis strain and to study its in vitro and in vivo thrombolytic activities.

METHODS

Employed fibrin plate method, pyrogenation (heating up) fibrin plate method and SDS-PAGE were used respectively to study FSC2-13 hydrolyzing fibrin and fibrinogen in vitro. Investigations were made on its in vivo pharmacodynamics using rat thrombogenesis inhibition model after it was administrated by intestinal route.

RESULTS

FSC2-13 could hydrolyze fibrin and fibrinogen in vitro and had hydrolysis sites on three peptide chains of fibrinogen. FSC2-13 could significantly inhibit the formation of rat venous thrombus after being administrated by intestinal route. Thrombogenesis inhibition rate was 68%. Activated partial thromboplastin time increased by 51%, fibrinogen content decreased by 49%, fibrin degradation product (FDP) content also increased obviously, but the plasminogen content did not change obviously.

CONCLUSION

FSC2-13 possessed in vitro and in vivo thrombolytic activities in a special way. There seem to be prospects for researches to develop it into a new generation of oral thrombolytic drug.

Purification of a fibrinolytic enzyme (myulchikinase) from pickled anchovy and its cytotoxicity to the tumor cell lines

A fibrinolytic enzyme, myulchikinase, from a Korean seasoning ingredient, myul-chi-jeot-gal, has been purified to electrophoretic homogeneity. The molecular mass of the myulchikinase was estimated to about 28 kDa by SDS-PAGE and gel filtration. Amino acid sequence of the NH2-terminal of myulchikinase showed significant homology with other fibrinolytic enzymes including trypsin from starfish, katsuwokinase, and rat pancreatic elastase II. The purified myulchikinase hydrolyzed various synthetic substrates with different substrate specificity and cytotoxic to the tumor cell lines.

Use of Sulfated Fucans as Anticoagulant and Antithrombotic Agents: Future Perspectives

Sulfated alpha-L-fucans from brown algae (also known as fucoidan) have complex and heterogeneous structures but recent studies revealed the occurrence of ordered repeat units in the sulfated fucans from several species. Even in these cases, the presence of highly branched portions and the complex distributions of sulfate and acetyl groups highlight the heterogeneity of algal fucans. Another source of sulfated alpha-L-fucans (and their parental compounds sulfated alpha-L-galactans and fucosylated chondroitin sulfate) is marine invertebrates. The invertebrate polysaccharides have simple, ordered structures, which differ in the specific patterns of sulfation and/or position of the glycosidic linkages within their repeating units. The algal and invertebrate sulfated fucans have potent anticoagulant activity, mediated by antithrombin and/or heparin cofactor II. As most of the studies were carried out with algal fucans it was not easy to trace a structure versus activity relationship. This aspect was clarified as studies were extended to invertebrate polysaccharides. These definitively established that regular, linear sulfated alpha-L-fucans and sulfated alpha-L-galactans express anticoagulant activity, which is not simply a function of charge density, but depends critically on the pattern of sulfation and monosaccharide composition. Sulfated alpha-L-fucans and fucosylated chondroitin sulfate also express antithrombotic activity when tested on in vivo models of venous and arterial thrombosis in experimental animals. These polysaccharides constitute potential therapeutic compounds as alternative to heparin and may help to design structure-based drugs with specific activity on each type of thrombosis episode and few side effects. They can also serve as research reagents to investigate and distinguish among a variety of interrelated events, such as coagulation, bleeding, thrombosis and platelet aggregation.

Purification and Characterization of Six Fibrinolytic Serine-Proteases from Earthworm Lumbricus rubellus

The six lumbrokinase fractions (F1 to F6) with fibrinolytic activities were purified from earthworm Lumbricus rubellus lysates using the procedures of autolysis, ammonium sulfate fractionation, and column chromatography. The proteolytic activities on the casein substrate of the six iso-enzymes ranged from 11.3 to 167.5 unit/mg with the rank activity orders of F2 > F1 > F5 > F6 > F3 > F4. The fibrinolytic activities of the six fractions on the fibrin plates ranged from 20.8 to 207.2 unit/mg with rank orders of F6 > F2 > F5 > F3 > F1 > F4. The molecular weights of each iso-enzyme, as estimated by SDS-PAGE, were 24.6 (F1), 26.8 (F2), 28.2 (F3), 25.4 (F4), 33.1 (F5), and 33.0 kDa (F6), respectively. The plasminogen was activated into plasmin by the enzymes. The optimal temperature of the six iso-enzymes was 50 degrees C, and the optimal pH ranged from pH 4-12. The four iso-enzymes (F1-F4) were completely inhibited by PMSF. The two enzymes (F5 and F6) were completely inhibited by aprotinin, TLCK, TPCK, SBTI, LBTI, and leupeptin. The N-terminal amino acid (aa) sequences of the first 20 to 22 residues of each fraction had high homology. All six iso-enzymes had identical aa residues 2-3 and 13-15. The N-terminal 21-22 aa sequences of the F2, F3, and F4 iso-enzymes were almost the same. The N-terminal aa sequences of F5 and F6 were identical.

Construction, expression, and characterization of a recombinant annexin B1-low molecular weight urokinase chimera in Escherichia coli

To produce a thrombi-targeting plasminogen activator, low molecular weight single-chain urokinase gene (scuPA32k) was spliced with the full-length cDNA of annexin B1 gene (anxB1) by overlap extension method. The fused gene anxB1scuPA was ligated into pET28a vector, transformed into E. coli BL21-RIL, and then induced to express under the control of T7 promoter. The AnxB1ScuPA protein expressed amounted to 22% of the total bacterial proteins. The product was refolded, and then purified by using DEAE Sepharose fast flow ion-exchange column and Superdex S-200 gel-filtration column. HPLC analysis revealed that the final purity is about 95%. The specific activity of AnxB1ScuPA, measured as amidolytic activity, reached 100,000 IU/mg. It had a similar S2444 catalytic efficiency (kcat/Km) to ScuPA32k, and also showed high activated-platelet membrane-binding activity and anticoagulant activity, indicating that the chimera fully retained the components of enzymatic and membrane-binding activities of the parent molecules. In vivo test revealed that, the dogs administered with AnxB1ScuPA had less reperfusion time, higher reperfusion ratio, and less bleeding effects than those with urokinase. These findings indicated that AnxB1ScuPA might have advantages over current available thrombolytic agents.

Streptokinase—a clinically useful thrombolytic agent

A failure of hemostasis and consequent formation of blood clots in the circulatory system can produce severe outcomes such as stroke and myocardial infraction. Pathological development of blood clots requires clinical intervention with fibrinolytic agents such as urokinase, tissue plasminogen activator and streptokinase. This review deals with streptokinase as a clinically important and cost-effective plasminogen activator. The aspects discussed include: the mode of action; the structure and structure-function relationships; the structural modifications for improving functionality; recombinant streptokinase; microbial production; and recovery of this protein from crude broths.

[Effect of ligustrazine on proliferative glomerulonephritis]

OBJECTIVE

To investigate the therapeutic effect of ligustrazine on proliferative nephritis.

METHODS

45 patients with mesangial cell proliferation were randomly divided into two groups according to age, clinical manifestations and the pathological lesions. Steroid, cyclophosphamide, losartan and dipyridamole were given to 20 patients in the control group. Ligustrazine with the dosage of 80 mg twice a day was given to 25 patients in the treatment group by intravenous perfusion besides the medicine used in the control group. The course of ligustrazine treatment lasted three weeks.

RESULT

The proteinuria and hematuria were decreased significantly with the increases of urine volume, serum albumin and creatinine clearance after ligustrazine treatment. The improvement of serum albumin, proteinuria and hematuria in the treated group were significant compared with control group after treatment.

CONCLUSION

Ligustrazine is eutherapeutic in treating proliferative glomerulonephritis, with the less risk of hemorrhage, ligustrazine can be used for long-term treatment without special monitored.