Crystal structure of earthworm fibrinolytic enzyme component B: a novel, glycosylated two-chained trypsin

Optimization of High-Activity earthworm fibrinolytic enzyme extraction methods and protein component analysis

OBJECTIVE

Optimize the extraction process of earthworm fibrinolytic enzyme.

METHODS

Chinese common earthworms underwent a series of purification processes, including grinding, salting out, hydrophobic medium chromatography, ammonium sulfate precipitation, and ion exchange chromatography, to obtain purified earthworm fibrinolytic enzyme.

RESULTS

Utilizing Pheretima aspergillum as the starting material, we discovered that the specific activity of lumbrokinase extracted via ammonium sulfate precipitation was 58 U/mg, noticeably surpassing that achieved through heat precipitation and ethanol precipitation methods. After undergoing two rounds of chromatographic separations employing hydrophobic affinity chromatography and anion exchange chromatography, the specific activity of the lumbrokinase protein soared to 9267 U/mg, significantly exceeding the 3,178 U/mg specific activity attained through industrial extraction methods.

DISCUSSION

The development of a novel crude extraction method for lumbrokinase protein can significantly boost its activity and purity. The discovery of a high-efficiency purification method and the identification of protein components within highly active lumbrokinase pave the way for further investigations into these proteins.

Autophagy of Candida albicans cells after the action of earthworm Venetin-1 nanoparticle with protease inhibitor activity

The present studies show the effect of the Venetin-1 protein-polysaccharide complex obtained from the coelomic fluid of the earthworm Dendrobaena veneta on Candida albicans cells. They are a continuation of research on the mechanisms of action, cellular targets, and modes of cell death. After the action of Venetin-1, a reduced survival rate of the yeast cells was noted. The cells were observed to be enlarged compared to the controls and deformed. In addition, an increase in the number of cells with clearly enlarged vacuoles was noted. The detected autophagy process was confirmed using differential interference contrast, fluorescence microscopy, and transmission electron microscopy. Autophagic vesicles were best visible after incubation of fungus cells with the Venetin-1 complex at a concentration of 50 and 100 µg mL-1. The changes in the vacuoles were accompanied by changes in the size of mitochondria, which is probably related to the previously documented oxidative stress. The aggregation properties of Venetin-1 were characterized. Based on the results of the zeta potential at the Venetin-1/KCl interface, the pHiep = 4 point was determined, i.e. the zeta potential becomes positive above pH = 4 and is negative below this value, which may affect the electrostatic interactions with other particles surrounding Venetin-1.

Cost-effective fibrinolytic enzyme production by microalga Dunaliella tertiolecta using medium supplemented with corn steep liquor

A fibrinolytic enzyme from the microalga Dunaliella tertiolecta was produced under mixotrophic conditions using different corn steep liquor (CSL) concentrations ( 0 ≤ CLS ≤ 0.75%), purified using a combination of salting out and ion-exchange chromatography, and then biochemical characterized. Cultivation of this microalga using 0.5% CSL led to the highest maximum cell concentration (1.960±0.010 mg L-1) and cell productivity (0.140g L-1 day-1), besides a high fibrinolytic activity of the extract obtained by the homogenization method (102 ±1 U mL-1). The enzyme extracted from the microalgal biomass was 5-fold purified with a 20% yield and was found to have a specific activity of 670 U mg-1. The enzyme, whose molecular weight determined by fibrin zymography was 10 kDa, was shown to be stable at pH 3.0-9.0 and up to 70°C with optimal pH and temperature values of 8.0 and 50°C, respectively. When compared to other fibrinolytic enzymes, this protease stood out for its high fibrinolytic activity, which was enhanced by Fe2+, inhibited by Zn2+, Cu2+, Mg2+, and Ca2+, and strongly inhibited by phenylmethylsulfonyl fluoride, suggesting that it belongs to the serine metalloprotease family. Moreover, thanks to its thermal stability, the enzyme may be easily preserved and activated under high-temperature conditions.

Development of a novel heterologous gene expression system using earthworms

In recent years, animals and plants have received increasing attention as potential next-generation protein production systems, especially for biopharmaceuticals and animal proteins. The aim of the present study was to develop the earthworms Eisenia fetida Waki and Eisenia andrei Sagami as next-generation animal protein production hosts. These earthworms have been approved as model animals for acute toxicity tests by the Organization for Economic Co-operation and Development, and they have post-translational modification systems. However, so far, none of the studies have used earthworm transfection techniques. Thus, we developed a transfection method for E. fetida and E. andrei using microinjection and electroporation systems. The maximum survival rates and transfection efficiencies were 79.2% and 29.2% for E. fetida, and 95.8% and 50.0% for E. andrei, respectively. Furthermore, human erythropoietin was detected in the transformed earthworm tail fragments using an enzyme-linked immunosorbent assay. These results contribute to the development of a potential earthworm-based novel animal protein production system.

Ligand-induced transition in conformations of vicinal cysteine disulfides in proteins

Vicinal cysteine disulfides are thought to be associated with specific conformations of cysteine disulfides due to the restricted rotation of single bonds in an eight-membered cyclic disulfide loop. Conformations of vicinal cysteine disulfides are analyzed using χ₁ , χ₂ , χ₃ , χ₂ ', χ₁ ' torsion angles in the crystal structures of proteins retrieved from Protein Data Bank (PDB). 85% of vicinal disulfides have (+, -)LHStaple conformation with trans configuration of the peptide bond and 9% have (-, -)RHStaple conformation with cis configured peptide bond. Conformational analysis of dipeptide Cys-Cys vicinal disulfide by density functional theory (DFT) further supported (+, -)LHStaple, (-, -)RHStaple, and (+, +)RHStaple as the preferred conformations of vicinal disulfides. Interestingly, the rare conformations of vicinal disulfides are observed in the ligand-bound forms of proteins and have higher disulfide strain energy. Conformations of vicinal disulfides in palmitoyl protein thioesterase 1, AChBP, and α7 nicotinic receptor are changed from preferred (+, -)LHStaple to rare (+, -)AntiLHHook/(+, -)AntiRHHook/(+, +)RHStaple conformation due to binding of ligands. Surprisingly, ligands are proximal to the vicinal disulfides in protein complexes that exhibited rare conformations of vicinal disulfides. The report has identified (+, -) LHStaple/(-, -) RHStaple as the hallmark conformations of vicinal disulfides and unraveled ligand-induced transition in conformations of vicinal cysteine disulfides in proteins.

A novel serine protease with anticoagulant and fibrinolytic activities from the fruiting bodies of mushroom Agrocybe aegerita

A novel fibrinolytic enzyme, ACase was isolated from fruiting bodies of a mushroom, Agrocybe aegerita. ACase was purified by using ammonium sulfate precipitation, gel filtration, ion exchange and hydrophobic chromatographies to 237.12 fold with a specific activity of 1716.77 U/mg. ACase was found to be a heterodimer with molecular mass of 31.4 and 21.2 kDa by SDS-PAGE and appeared as a single band on Native-PAGE and fibrin-zymogram. The N-terminal sequence of the two subunits of ACase was AIVTQTNAPWGL (subunit 1) and SNADGNGHGTHV (subunit 2). ACase had maximal activity at 47 °C and pH 7.6. It's activity was improved by Cu²⁺, Na⁺, Fe³⁺, Zn²⁺, Ba²⁺, K⁺ and Mn²⁺, but inhibited by Fe²⁺, Mg²⁺ and Ca²⁺. PMSF, SBTI, aprotinine and Lys inhibited the enzyme activity, which suggested that ACase was a serine protease. ACase could degrade all three chains (α, β and γ) of fibrinogen. Moreover, the enzyme acted as both, a plasmin-like fibrinolytic enzyme and a plasminogen activator. It could hydrolyze human thrombin slightly, which indicated that the ACase could inhibit the activity of thrombin and acted as an anticoagulant to prevent thrombosis. Based on these results, ACase might act as a therapeutic agent for treating thrombosis, or as a functional food. Further investigation of the enzyme is underway.

Stenotrophomonas maltophilia Gd2: A potential and novel isolate for fibrinolytic enzyme production

The bacterium with an ability to produce extracellular fibrinolytic protease was isolated and identified as Stenotrophomonas maltophilia Gd2 based on ribotyping. The in-vitro fibrinolytic profile of this enzyme depicted 73% of fibrin clot dissolution within 4 h. Fibrinolytic enzyme yield influenced by different physiological (incubation time, temperature, agitation and pH), nutritional (macronutrients such as carbon and nitrogen sources) and biological (inoculums age and inoculums concentration) parameters of fermentation which were optimized based on one-factor-at-a-time (OFAT) approach. The enzyme yield improved from 886 to 1795 FU ml-1 upon OFAT; optimized conditions include temperature - 33 °C, pH - 8.0, incubation time - 36 h, agitation - 150 RPM, 3% v/v inoculums and age of inoculum - 18 h. Further optimization of enzyme production was achieved with implementation of Plackett-Burman media designing where the production levels increased to 3411 FU ml-1 and noticed that peptone, pH, dextrose and K2HPO4 was found to be significant factor. This ms reports the highest fibrinolytic enzyme yield with S. maltophilia to that of literature reports.

Specific DNA identification of Pheretima in the Naoxintong capsule

Background

Pheretima is a minister drug in Naoxintong capsule (NXTC), a well-known traditional Chinese medicine (TCM) formula for the treatment of cardiovascular and cerebrovascular diseases. Owing to the loss of morphological and microscopic characteristics and the lack of recognized chemical marker, it is difficult to identify Pheretima in NXTC. This study aims to evaluate the feasibility of using DNA techniques to authenticate Pheretima, especially when it is processed into NXTC.

Methods

DNA was extracted from crude drugs of the genuine and adulterant species, as well as nine batches of NXTCs. Based on mitochondrial cytochrome c oxidase subunit I (COI) gene, specific primers were designed for two genera of genuine species, Metaphire and Amynthas, respectively. PCR amplification was performed with the designed primers on crude drugs of Pheretima and NXTCs. The purified PCR products were sequenced and the obtained sequences were identified to species level with top hit of similarity with BLAST against GenBank nucleotide database.

Results

Primers MF2R2 and AF3R1 could amplify specific DNA fragments with sizes around 230–250 bp, both in crude drugs and NXTC. With sequencing and the BLAST search, identities of the tested samples were found.

Conclusion

This study indicated that the molecular approach is effective for identifying Pheretima in NXTC. Therefore, DNA identification may contribute to the quality control and assurance of NXTC.

Anti-Candida albicans effect of the protein-carbohydrate fraction obtained from the coelomic fluid of earthworm Dendrobaena veneta

An antifungal active fraction (AAF) from the coelomic fluid (CF) of the earthworm Dendrobaena veneta was isolated. The aim of the study was to analyze the antifungal activity of the AAF and to carry out chemical characterization of the fraction. The active fraction showed antifungal activity against a clinical C. albicans isolate, C. albicans ATCC 10231, and C. krusei ATCC 6258. It effectively reduced the metabolic activity of C. albicans cells and influenced their morphology after 48 hours of incubation. Scanning electron microscopy (SEM) images revealed loss of integrity of the cell wall induced by the active fraction. Calcofluor White staining showed changes in the structure of the C. albicans cell wall induced by the AAF. The fungal cells died via apoptosis and necrosis after the treatment with the studied fraction. Electrophoresis under native conditions revealed the presence of two compounds in the AAF, while SDS/PAGE gel electrophoresis showed several protein and carbohydrate compounds. The active fraction was analyzed using Raman spectroscopy, MALDI TOF/TOF, and ESI LC-MS. The Raman analysis confirmed the presence of proteins and determined their secondary structure. The MALDI TOF/TOF analysis facilitated detection of four main compounds with a mass of 7694.9 m/z, 12292.3 m/z, 21628.3 m/z, and 42923.2 m/z in the analyzed fraction. The presence of carbohydrate compounds in the preparation was confirmed by nuclear magnetic resonance (NMR) and gas chromatography (GC-MS). The ATR-FTIR spectrum of the AAF exhibited high similarity to the spectrum of egg white lysozyme. The AAF showed no endotoxicity and cytotoxicity towards normal skin fibroblasts (HSF); therefore, it can be used for the treatment of skin and mucous membrane candidiasis in the future. Given its efficient and selective action, the fraction seems to be a promising preparation with antifungal activity against C. albicans.

Purification, biochemical, and thermal properties of fibrinolytic enzyme secreted by Bacillus cereus SRM-001

The discovery of microbial fibrinolytic enzymes is essential to treat cardiovascular diseases. This study reports the discovery of a fibrinolytic enzyme secreted by Bacillus cereus SRM-001, a microorganism isolated from the soil of a chicken waste-dump yard. The B. cereus SRM-001 was cultured and the secreted fibrinolytic enzyme purified to show that it is a ∼28 kDa protein. The purified enzyme was characterized for its kinetics, biochemical and thermal properties to show that it possesses properties similar to plasmin. A HPLC-MS/MS analysis of trypsin digested protein indicated that the fibrinolytic enzyme shared close sequence homology with serine proteases reported for other Bacillus sp. The results show that the B. cereus SRM-001 secreted enzyme is a ∼28 kDa serine protease that possesses fibrinolytic potential.

Enzyme promiscuity in earthworm serine protease: substrate versatility and therapeutic potential

Enzymes are the most versatile molecules in the biological world. These amazing molecules play an integral role in the regulation of various metabolic pathways and physiology subsequently. Promiscuity of an enzyme is the capacity to catalyze additional biochemical reactions besides their native one. Catalytic promiscuity has shown great impact in enzyme engineering for commercial enzyme and therapeutics with natural or engineered catalytic promiscuity. The earthworm serine protease (ESP) is a classic example of enzyme promiscuity and studied for its therapeutic potential over the last few decades. The ESP was reported for several therapeutic properties and fibrinolytic activity has been much explored. ESP, a complex enzyme exists as several isoforms of molecular weight ranging from 14 to 33 kDa. The fibrinolytic capacity of the enzyme has been studied in different species of earthworm and molecular mechanism is quite different from conventional thrombolytics. Cytotoxic and anti-tumor activities of ESP were evaluated using several cancer cell lines. Enzyme had shown tremendous scope in fighting against plant viruses and microbes. ESP is also reported for anti-inflammatory activity and anti-oxidant property. Apart from these, recently, ESP is reported for DNase activity. The daunting challenge for researchers is to understand the molecular mechanism for such diverse properties and possibility of enzyme promiscuity. This review emphasizes molecular mechanism of ESP governing various biochemical reactions. Further, the concept of enzyme promiscuity in ESP towards development of novel enzyme based drugs has been reviewed in this study.

Rapid extraction and purification of lumbrokinase from Lumbricus rubellus using a hollow fiber membrane and size exclusion chromatography

OBJECTIVES

To develop a purification process using hollow fiber membrane separation combined with size exclusion chromatography for the extraction of lumbrokinase from earthworms (Lumbricus rubellus).

RESULTS

To extract the protein, the earthworms were first homogenized for 10 min, to produce ultrafine particles. Polyether sulfone hollow fiber membranes with MW cut offs of 50 and 6 kDa were used for initial purification of the crude extract. Further purification was carried out on a Sephadex G-75 column, and yielded three fractions of high purity protein. One of these fractions showed fibrinolytic activity.

CONCLUSIONS

Three samples of high purity protein were obtained and one protein (LK1) showed strong fibrinolytic activity. The method has higher purification efficiency in comparison with existing methods.

Bioactive proteins and peptides isolated from Chinese medicines with pharmaceutical potential

Some protein pharmaceuticals from Chinese medicine have been developed to treat cardiovascular diseases, genetic diseases, and cancer. Bioactive proteins with various pharmacological properties have been successfully isolated from animals such as Hirudo medicinalis (medicinal leech), Eisenia fetida (earthworm), and Mesobuthus martensii (Chinese scorpion), and from herbal medicines derived from species such as Cordyceps militaris, Ganoderma, Momordica cochinchinensis, Viscum album, Poria cocos, Senna obtusifolia, Panax notoginseng, Smilax glabra, Ginkgo biloba, Dioscorea batatas, and Trichosanthes kirilowii. This article reviews the isolation methods, molecular characteristics, bioactivities, pharmacological properties, and potential uses of bioactive proteins originating from these Chinese medicines.

Recombinant protein production of earthworm lumbrokinase for potential antithrombotic application

Earthworms have been used as a traditional medicine in China, Japan, and other Far East countries for thousands of years. Oral administration of dry earthworm powder is considered as a potent and effective supplement for supporting healthy blood circulation. Lumbrokinases are a group of enzymes that were isolated and purified from different species of earthworms. These enzymes are recognized as fibrinolytic agents that can be used to treat various conditions associated with thrombosis. Many lumbrokinase (LK) genes have been cloned and characterized. Advances in genetic technology have provided the ability to produce recombinant LK and have made it feasible to purify a single lumbrokinase enzyme for potential antithrombotic application. In this review, we focus on expression systems that can be used for lumbrokinase production. In particular, the advantages of using a transgenic plant system to produce edible lumbrokinase are described.

Biochemical characteristics of a fibrinolytic enzyme purified from a marine bacterium, Bacillus subtilis HQS-3

A fibrinolytic enzyme isolated from marine Bacillus subtilis HQS-3 was purified to electrophoretic homogeneity using ammonium sulphate precipitation, alkaline solution treatment, membrane concentration, dialysis, ion exchange, and gel filtration chromatography. SDS-PAGE and gel filtration chromatography showed that it was a monomeric protein with an apparent molecular weight of 26 kDa. The purified enzyme was active at pH 6.0-10.0 with an optimum pH of 8.0. It was stable at temperatures ranging from 25 to 37 °C, exhibiting maximum activity between 45 °C and 50 °C. The isoelectric point of the enzyme was 9.0-9.2, which was higher than those of other known fibrinolytic enzymes from Bacillus species. PMSF, EDTA, Cu(2+), Zn(2+), and Co(2+) inhibited the enzyme activity significantly. This enzyme did not cause hemolysis in vitro and preferred direct degradation of fibrin in the following order: α, β, and γ-γ chains. Thus, these results suggest that the marine-derived enzyme is a plasmin-like serine metalloprotease, which is distinct from other fibrinolytic enzymes from genus Bacillus.

Cloning, expression and characterization of a gene from earthworm Eisenia fetida encoding a blood-clot dissolving protein

A lumbrokinase gene encoding a blood-clot dissolving protein was cloned from earthworm (Eisenia fetida) by RT-PCR amplification. The gene designated as CST1 (GenBank No. AY840996) was sequence analyzed. The cDNA consists of 888 bp with an open reading frame of 729 bp, which encodes 242 amino acid residues. Multiple sequence alignments revealed that CST1 shares similarities and conserved amino acids with other reported lumbrokinases. The amino acid sequence of CST1 exhibits structural features similar to those found in other serine proteases, including human tissue-type (tPA), urokinase (uPA), and vampire bat (DSPAα1) plasminogen activators. CST1 has a conserved catalytic triad, found in the active sites of protease enzymes, which are important residues involved in polypeptide catalysis. CST1 was expressed as inclusion bodies in Escherichia coli BL21(DE3). The molecular mass of recombinant CST1 (rCST) was 25 kDa as estimated by SDS–PAGE, and further confirmed by Western Blot analysis. His-tagged rCST1 was purified and renatured using nickel-chelating resin with a recovery rate of 50% and a purity of 95%. The purified, renatured rCST1 showed fibrinolytic activity evaluated by both a fibrin plate and a blood clot lysis assay. rCST1 degraded fibrin on the fibrin plate. A significant percentage (65.7%) of blood clot lysis was observed when blood clot was treated with 80 mg/mL of rCST1 in vitro. The antithrombotic activity of rCST1 was 912 units/mg calculated by comparison with the activity of a lumbrokinase standard. These findings indicate that rCST1 has potential as a potent blood-clot treatment. Therefore, the expression and purification of a single lumbrokinase represents an important improvement in the use of lumbrokinases.

A high molecular weight protein extract of Mastobranchus indicus (Mi-64) having antiarthritic activity in experimental animals

Mi-64, a high molecular weight protein (130 kDa), obtained from the tissue homogenate of marine polychaete (Mastobranchus indicus) collected from the Indian Sunderban has antiarthritic activity in experimental animals. The FCA-induced arthritis model was developed in Wistar albino rats to evaluate the antiarthritic effects of Mi-64. After FCA induction, the rats were treated with Mi-64 (0.25 and 0.5 mg kg(-1) body weight) for 10 days. We have determined the paw/ankle swellings, urinary hydroxyproline and glucosamine, serum acid and alkaline phosphatases to assess the antiarthritic activity. The levels of interleukin-1 beta (IL-1β), IL-6, cytokine-induced neutrophil chemoattractant-1 (CINC-1), tumor necrosis factor-alpha (TNF-α), and IL-10 were measured by ELISA. Results showed that Mi-64 significantly reduced paw/ankle swellings and restored the urinary hydroxyproline/glucosamine and serum phosphatases. Mi-64 significantly inhibited the overproduction of IL-1β, IL-6, CINC-1, and TNF-α and augmented IL-10 production. The data suggest that Mi-64 produced significant antiarthritic effects that may be mediated by balancing the pro- and anti-inflammatory cytokines.

Purification and characterization of novel fibrinolytic proteases as potential antithrombotic agents from earthworm Perionyx excavatus

Six protease fractions, namely FI, FII, FIII-1, FIII-2, FIII-3 and FIV, were isolated from Perionyx excavatus earthworm biomass by acetone precipitation, followed by serial chromatography using anion exchange, hydrophobic interaction and size exclusion chromatography. All fractions exhibited strong hydrolytic activity towards casein. The activity of six fractions towards fibrin, determined by fibrin plate assay, ranged from 44 to 831 plasmin unit.mg-1 and ranked as FIII-3 > FIII-2 > FI > FIII-1 > FIV > FII. Casein degradation was optimal at pH 7 and 11, and at 45-60°C. All fractions were considerably stable at high temperature and wide pH range. They were completely inhibited by phenylmethylsulfonyl fluoride (PMSF). The molecular weights (MW) and isoelectric points (pI) determined by 2D-electrophoresis were 27.5-34.5 kDa, and 4.3-5.2, respectively. Tandem mass spectrometry (MS) analysis was used to deduce the amino acid sequences of some peptides from FIII-1 and FIII-2. The sequences shared 16.9% and 13.2% similarity, respectively, with the fibrinolytic enzymes from two related earthworm species, Lumbricus rubellus and Eisenia fetida. The P. excavatus proteases were classified as serine proteases. They could perform rapid hydrolysis on both coagulated fibrous fibrin and soluble fibrinogen monomers without the presence of activators such as tPA or urokinase.

Purification of a protein from coelomic fluid of the earthworm Eisenia foetida and evaluation of its hemolytic, antibacterial, and antitumor activities

CONTEXT

Earthworm Eisenia foetida (Lumbricus rubellus), a traditional Chinese medicine, is used for treating many diseases, and its coelomic fluid has extensive biological functions.

OBJECTIVE

The hemolytic, antibacterial and antitumor activities of an earthworm protein purified from coelomic fluid were investigated in vitro.

MATERIALS AND METHODS

We used ultrafiltration, gel chromatography, and ion exchange chromatography in sequence to isolate and purify an earthworm protein from coelomic fluid (ECFP), and ECFP was characterized by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Hemolytic assay and antibacterial tests were applied to determine the cytolytic activity of ECFP. The MTT method was carried out to evaluate the antitumor effect of ECFP on HeLa cells and LTEP-A2 cells.

RESULTS

ECFP, with molecular weight determined to be approximately 38.6 kilodaltons (KDa), was shown to possess significant hemolytic activity to chicken red blood cells (CRBC) (minimal hemolytic concentration 0.39 µg/mL). Antibacterial effect of ECFP obviously tested against Escherichia coli (minimal bactericidal concentration, MBC 180 µg/ mL) and Staphylococcus aureus (MBC 90 µg/mL) were observed. Moreover, ECFP notably inhibited the proliferation of HeLa cells (IC₅₀ 77 µg/mL) and LTEP-A2 cells (IC₅₀ 126 µg/mL) both in a time- and dose-dependent manner.

DISCUSSION AND CONCLUSION

ECFP could serve as a component of the innate defense system of earthworms against foreign organisms, and thus it has potential pharmaceutical application in the future.

Purification and characterization of a novel fibrinolytic enzyme from fruiting bodies of Korean Cordyceps militaris

A fibrinolytic enzyme has been purified from the fruiting bodies of Korean Cordyceps militaris. The molecular mass of the enzyme was estimated to be 34 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), fibrin-zymography, and gel filtration chromatography. The 15 amino acid residues of the N-terminal sequence of the enzyme were APVEQCDAPVGLARL, which is dissimilar to those of fibrinolytic enzymes from other mushrooms. Optimal pH and temperature values of the enzyme were 7.0 and 40°C, respectively. The enzyme activity was completely inhibited by phenylmethylsulfonyl fluoride (PMSF), TPCK, 1,10-phenanthroline, Cu(2+), and Ba(2+). It was also significantly inhibited by aprotinin, EDTA, and EGTA. The enzyme showed a higher specificity for a synthetic substrate, N-succinyl-Ala-Ala-Pro-Phe-p-nitroanilide, exhibiting that it is a chymotrypsin-like serine metalloprotease. The enzyme preferentially hydrolyzed the fibrinogen Aα-, followed by the Bβ-chains and the γ-chain. The α, β, and γ-γ chains of fibrin were also degraded by the enzyme.

Eisenia fetida protease-III-1 functions in both fibrinolysis and fibrogenesis

The fibrinolytic function of earthworm protease-III-1 (Ef P-III-1) has been studied in recent years. Here, we found that Ef P-III-1 acted not only in fibrinogenolysis, but also in fibrogenesis. We have used Ef P-III-1 to hydrolyze fibrinogen, and to activate plasminogen and prothrombin. Based on the N-terminal sequences of the hydrolytic fragments, Ef P-III-1 was showed to specifically recognize the carboxylic sites of arginine and lysine. Analyses by fibrinogenolysis mapping and amino acid sequencing revealed that the isozyme could cleave the alpha, beta, and gamma chains of fibrinogen, showing a high α-fibrinogenase, moderate β-fibrinogenase, and low γ-fibrinogenase activities. Interestingly, Ef P-III-1 activated plasminogen and released active plasmin, suggesting a tPA-like function. Furthermore, Ef P-III-1 showed a factor Xa-like function on prothrombin, producing alpha-thrombin. The function in both activating prothrombin and catalyzing fibrinogenolysis suggests that Ef P-III-1 may play a role in the balance between procoagulation and anticoagulation.

Expression, purification, and characterization of recombinant lumbrokinase PI239 in Escherichia coli

Lumbrokinase (LK) is an important fibrinolytic enzyme derived from earthworms. It has been found that LK is composed of a group of isoenzymes. To construct and express the mature peptide of LK PI239 in Escherichia coli, we amplified and optimized the gene of LK which was then cloned into the prokaryotic expression vector pET-22b(-). The recombinant LK (rLK) protein was expressed as inclusion bodies and we have developed a purification process of rLK from these inclusion bodies. A step-down urea concentration strategy was applied to the rLK renaturation process. The purified and renatured rLK apparently ameliorated the conditions of the model thrombosis rats used, and may be developed into a therapeutic agent for thrombotic-associated diseases.

Purification and characterization of fibrinolytic metalloprotease from Perenniporia fraxinea mycelia

In this study we purified and characterized a fibrinolytic protease from the mycelia of Perenniporia fraxinea. The apparent molecular mass of the purified enzyme was estimated to be 42kDa by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE), fibrin zymography and size exclusion using fast protein liquid chromatography (FPLC). The first 20 amino acid residues of the N-terminal sequence were ASYRVLPITKELLPPEFFVA, which shows a high degree of similarity with a fungalysin metallopeptidase from Coprinopsis cinerea. The optimal reaction pH value and temperature were pH 6.0 and 35-40 degrees C, respectively. Results for the fibrinolysis pattern showed that the protease rapidly hydrolyzed the fibrin alpha-chain followed by the beta-chain. The gamma-gamma chains were also hydrolyzed, but more slowly. The purified protease effectively hydrolyzed fibrinogen, preferentially digesting the Aalpha-chains of fibrinogen, followed by Bbeta- and gamma-chains. We found that protease activity was inhibited by Cu(2+), Fe(3+), and Zn(2+), but enhanced by the additions of Mn(2+), Mg(2+) and Ca(2+) metal ions. Furthermore, the protease activity was inhibited by EDTA, and it was found to exhibit a higher specificity for the chromogenic substrate S-2586 for chymotrypsin, indicating that the enzyme is a chymotrypsin-like metalloprotease. The mycelia of P. fraxinea may thus represent a source of new therapeutic agents to treat thrombosis.

The expanding diversity of serine hydrolases

Serine hydrolases use a hydroxyl of a serine, assisted by one or more other residues, to cleave peptide bonds. They belong to several different families whose general mechanism is well known. However, the subtle structural differences that have recently been observed across a variety of families shed light on their functional diversity, including variations in mechanism of action, differences in the modes of substrate binding, and substrate-assisted orientation of catalytic residues. Of particular interest are the Rhomboid family serine proteinases that are active within the plasma membrane, for which several new structures have been reported. Because these enzymes are involved in biological and pathological processes, many are becoming important targets of drug design.

Biochemical and enzymatic properties of a novel marine fibrinolytic enzyme from Urechis unicinctus

A novel potent protease, Urechis unicinctus fibrinolytic enzyme (UFE), was first discovered by our laboratory. In this study, we further investigated the enzymatic properties and dynamic parameters of UFE. As a low molecular weight protein, UFE appeared to be very stable to heat and pH. When the temperature was <50 degrees C, the remnant enzyme activity remained almost unchanged, but when the temperature was raised to 60 degrees C the remnant enzyme activity began to decrease rapidly. UFE was quite stable in a pH range of 3.0-12.0, especially at slightly alkaline pH values. Mn(2+), Cu(2+), and Fe(2+) ions were activators of UFE, whereas Fe(3+) and Ag(+) ions were inhibitors. Fe(2+) ion along with Fe(3+) ion might regulate UFE activity in vivo. The optimum pH and temperature of UFE were about 8.0 and 50 degrees C, respectively. When using casein as substrate and a substrate concentration <0.1% casein (w/v), the reaction velocity was increased with substrate concentration. Also when using casein as substrate, the determined K(m) and V(max) of UFE were 0.5298 mg/mL and 3.0845 mol of L-tyrosine equivalent, respectively. Our systematic research results are significant when UFE is applied for medical and industrial purposes.

Purification and properties of the protease from Perinereis aibuhitensis Grube

AIM: To purify a new protease from the clamworm Perinereis aibuhitensis Grube, and study its properties.

METHODS: After homogenization, Superdex-75 chromatography, MonoQ^TM chromatography, and SP-Sepharose 4B chromatography were used ordinally to purify the protease from the clamworm Perinereis aibuhitensis Grube. A new gelatin zymography method was used to study the proteolytic activity of the protease: protease separated by non-reductive SDS-PAGE was electrophoretically transferred to a gel containing gelatin, and the proteolytic activity of the protease was determined by the clear zone of the electrophoretic protein band. The effect of pH value, temperature, protease inhibitor, organic solvents and metal ions on the proteolytic activity of the protease was studied.

RESULTS: After purification, one kind of protease was obtained, which showed two protein bands with molecular weights of 34900 and 33900 separately by reductive SDS-PAGE, while three bands with molecular weights of 65600, 57900, and 43500 separately by non-reductive SDS-PAGE. Gelatin zymography showed that the proteolytic activity mainly appeared around the band of M_r 66000. The protease was stable and displayed high proteolytic activity within the range of pH 8 to 10 and at 20-35 ℃ It was strongly inhibited by phenylmethyl sulfonyl fluoride (PMSF), while stable in the presence of organic solvents.

CONCLUSION: The protease is composed of two subunits, whose molecular weights are 33900 and 34900, respectively. Gelatin zymography is sensitive and effective in studying the proteolytic activity of proteases.

Glycosylated trypsin-like proteases from earthworm Eisenia fetida

Although groups of earthworm proteases have been found by several laboratories, it is still unclear how many of the isolated trypsin-like fibrinolytic enzymes are in glycosylated form. Here, eight glycosylated fibrinolytic proteases (EfP-0-1, EfP-0-2, EfP-I-1, EfP-I-2, EfP-II-1, EfP-II-2, EfP-III-1 and EfP-III-2) were isolated from an earthworm species (Eisenia fetida) through a stepwise-purification procedure: ammonium sulfate precipitation, affinity chromatography on a Sepharose-4B column coupled with soybean trypsin inhibitor (SBTI), and ionic chromatography with a DEAE-Cellulose-52 column. Among the eight purified trypsin-like glyco-proteases, EfP-0-2 and EfP-II-2 were newly isolated isozymes. Glycoprotein staining of the proteases on native-PAGE with a Schiff's reagent (sodium meta-periodate) revealed that the eight proteases were glycoproteins. Measurements of the glycan content with sodium meta-periodate and glycoprotein-test reagent showed that these proteases had different carbohydrate contents. Dot-blotting assay with ConA suggested the oligosaccharides were composed of mannose residues.

Purification and characterization of a fibrinolytic enzyme of Bacillus subtilis DC33, isolated from Chinese traditional Douchi

Bacillus subtilis DC33 producing a novel fibrinolytic enzyme was isolated from Ba-bao Douchi, a traditional soybean-fermented food in China. The strong fibrin-specific enzyme subtilisin FS33 was purified to electrophoretic homogeneity using the combination of various chromatographic steps. The optimum temperature, pH value, and pI of subtilisin FS33 were 55 degrees C, 8.0, and 8.7, respectively. The molecular weight was 30 kDa measured by SDS-PAGE under both reducing and non-reducing conditions. The enzyme showed a level of fibrinolytic activity that was about six times higher than that of subtilisin Carlsberg. The first 15 amino acid residues of N-terminal sequence of the enzyme were A-Q-S-V-P-Y-G-I-P-Q-I-K-A-P-A, which are different from that of other known fibrinolytic enzymes. The amidolytic activities of subtilisin FS33 were inhibited completely by 5 mM phenylmethanesulfonyl fluoride (PMSF) and 1 mM soybean trypsin inhibitor (SBTI), but 1,4-dithiothreitol (DTT), beta-mercaptoethanol, and p-hydroxymercuribenzoate (PHMB) did not affect the enzyme activity; serine and tryptophan are thus essential in the active site of the enzyme. The highest affinity of subtilisin FS33 was towards N-Succ-Ala-Ala-Pro-Phe-pNA. Therefore, the enzyme was considered to be a subtilisin-like serine protease. The fibrinolytic enzyme had a high degrading activity for the Bbeta-chains and Aalpha-chain of fibrin(ogen), and also acted on thrombotic and fibrinolytic factors of blood, such as plasminogen, urokinase, thrombin, and kallikrein. So subtilisin FS33 was able to degrade fibrin clots in two ways, i.e., (a) by forming active plasmin from plasminogen and (b) by direct fibrinolysis.

Isolation of a cDNA encoding a protease from Perinereis aibuhitensis Grube

The cDNA encoding a protease of Perinereis aibuhitensis Grube (PPA) was cloned. The deduced amino acid sequence analysis showed that the protein had 49% identity to the C-terminal amino acid 169-246 of serine protease of Heterodera glycines. Northern blotting analysis indicated that the cDNA could hybridize with mRNA of approximately 260 bases isolated from the marine earthworm. The cDNA was amplified by polymerase chain reaction and cloned into pMAL-p2 to construct expression vector pMAL-PPA. pMAL-PPA was introduced into Escherichia coli BL21(DE3) and overexpression of PPA fused with maltose binding protein was achieved by isopropyl-beta-D-thiogalactopyranoside induction. The fusion protein was purified by affinity chromatography on an amylose resin column and ion-exchange chromatography on a diethylaminoethyl-Sepharose 4B column. Rabbits were immunized with the purified protein and antiserum was prepared. The antibody could react with a protein of approximately 9 kDa extracted from the marine earthworm as shown by Western blotting analysis. The activity analysis of the recombinant PPA suggested that it was probably a plasminogen activator.

In situ localization and substrate specificity of earthworm protease-II and protease-III-1 from Eisenia fetida

Recently, the function in fibrinolysis of earthworm proteases has been studied. In our experiments, earthworm protease-II (EfP-II) and earthworm protease-III-1 (EfP-III-1) were isolated and purified from Eisenia fetida. As shown by the assay of sections of the earthworm on fibrin plates, the enzymic activity was mainly detected around the clitellum. In the presence of anti-EfP-II or anti-EfP-III-1 serum, the immunological signals of the two isozymes were clearly found in the anterior alimentary mucosa, suggesting that EfP-II and -III-1 are localized and expressed in intestinal epithelial cells. The Michaelis-Menten constant (K(m)) for EfP-III-1 reacting with BAEE is smaller (1.7x10(-5)M) in comparison with the K(m) values of other substrates such as Chromozym-Try and -TH (3.3-6.0x10(-5)M). This indicates that EfP-III-1 is a trypsin-like protein. EfP-II shows a strong trypsin-like, moderate elastase-like and weak chymotrypsin-like serine function. The relative broad substrate specificity of EfP-II and EfP-III-1 is consistent with their localization in the anterior alimentary canal where different micro-organisms and ingested proteins require to be digested.