This research was funded by the Science and Technology Bureau of Xiamen City (3502Z20227197) and the Science and Technology Bureau of Fujian Province (No. 2019J01070, No.2021Y0027).

1. Preparation
<ol>
	<li>Sample treatment
	<ol>
		<li>Carefully dissect fresh S. nudus (100 g) and collect the intestine and its inner fluid.</li>
		<li>Add 300 mL of Tris-HCl buffer (0.02 M, pH 7.4) for homogenization (1,000 rpm, 60 s).</li>
		<li>Freeze-thaw the homogenate 3x.</li>
		<li>Centrifuge the sample (10,956 &#215; g, 0.5 h, 4 &#176;C) and collect the supernatant. Store the sample at 4 &#176;C until further use.</li>
	</ol>
	</li>
	<li>Protein precipitation
	<ol>
		<li>Mix the supernatant with saturated ammonium sulfate solution (nine volumes) and let the mixture stand for 12 h at 4 &#176;C. 
		NOTE: The protocol can be paused here and continued later.</li>
		<li>Centrifuge (10,956 &#215; g, 0.5 h, 4 &#176;C) to obtain the protein precipitate; store it at 4 &#176;C for later use.</li>
	</ol>
	</li>
	<li>Protein resuspension
	<ol>
		<li>Resuspend the protein precipitate with 30 mL of Tris-HCl buffer (0.02 M, pH 7.4). Store this crude protein solution at 4 &#176;C for later use.</li>
	</ol>
	</li>
</ol>
2. Affinity chromatography
<ol>
	<li>Solution filtration
	<ol>
		<li>Filter the crude protein solution through a 0.22 &#181;m filter membrane. Store this sample at 4 &#176;C for later use.</li>
	</ol>
	</li>
	<li>Column packing
	<ol>
		<li>Pack the arginine-agarose matrix affinity chromatography column and lysine-agarose matrix affinity chromatography column by loading an appropriate amount of lysine-agarose matrix medium and arginine-agarose matrix medium into 5 mL empty chromatography columns. 
		NOTE: The column can be stored at 2-8 &#176;C, with the matrix immersed in store buffer (20% ethanol).</li>
	</ol>
	</li>
	<li>Affinity purification
	<ol>
		<li>Equilibrate the affinity chromatography column with ddH2O first (1 mL/min, 10 column volumes), followed by Tris-HCl buffer (0.02 M, pH 8.0, 1 mL/min, 5 column volumes).</li>
		<li>Load the protein solution sample onto the pre-equilibrated column (1 mL/min, 1/3 column volume). 
		NOTE: The volume of sample loading is dependent on the concentration of sFE.</li>
		<li>Wash the column with Tris-HCl buffer (0.02 M, pH 8.0, five column volumes).</li>
		<li>Elute the column with 0.15 M, 0.25 M, 0.35 M, 0.45 M, 0.55 M, and 0.65 M NaCl (1 mL/min, five column volumes) successively.</li>
		<li>Look for the elution peak that should appear in the 0.15 M NaCl elution, and then collect the fractions in 5 mL tubes.</li>
		<li>Concentrate the elution sample using a 3 kD ultra centrifugal filter (3,944 &#215; g, 1.5 h, 4 &#176;C). Store this sample at -80 &#176;C for later use.</li>
	</ol>
	</li>
</ol>
3. Purity assessment
<ol>
	<li>Sodium dodecyl-sulfate polyacrylamide gel electrophoresis (SDS-PAGE) gel preparation
	<ol>
		<li>Prepare the SDS-PAGE gel according to Laemmli&#39;s method using 5% concentrated gel and 12% separation gel13.</li>
	</ol>
	</li>
	<li>Electrophoresis
	<ol>
		<li>Mix the sample (15 &#181;L) with 5x SDS-PAGE protein loading buffer (1/4 volume), heat in boiling water for 5 min, load onto the SDS-PAGE gel, and run the gel at 80 V, 60 mA for 1.5 h.</li>
	</ol>
	</li>
	<li>Analysis
	<ol>
		<li>After electrophoresis, stain the gel with a Silver Stain Kit, according to the manufacturer&#39;s protocol, and observe the stained gel using a chemiluminescent imaging system.</li>
		<li>Analyze the purity of the target protein using the following formula: purity of target protein = intensity value of target protein/intensity value of total protein.</li>
	</ol>
	</li>
</ol>
4. Fibrinolytic activity evaluation
<ol>
	<li>Fibrin plate preparation
	<ol>
		<li>Prepare the fibrinogen solution by mixing 25 mg of fibrinogen with 1.25 mL of physiological saline.</li>
		<li>Prepare the thrombin solution by completely mixing 100 U of thrombin with 1.05 mL of physiological saline.</li>
		<li>Prepare the agarose solution by adding 0.5 g of agarose to 22.5 mL of Tris-HCl buffer (0.02 mol/L, pH 7.4). Mix and heat the agarose solution at 100 &#176;C until dissolved completely.</li>
		<li>Cool the agarose solution down to around 50 &#176;C and add fibrinogen solution. Then, immediately add the thrombin solution, mix them quickly, and pour them into a 60 mm culture dish.</li>
	</ol>
	</li>
	<li>Loading
	<ol>
		<li>Punch 3 mm wells on the prepared fibrin plates using a sterile borer and fill the wells with 10 &#181;L samples.</li>
	</ol>
	</li>
	<li>Analysis
	<ol>
		<li>After 18 h of incubation at 37 &#176;C, measure the fibrinolytic activity by calculating the size of their degrading zones. Fibrinolytic activity = (zone size of the sample/ zone size of urokinase) x 100 U. Zone size = diameter x diameter. 
		NOTE: Physiological saline buffer, crude protein (sample obtained in protocol step 1.3.1), and urokinase were used for the blank, negative control, and positive control, respectively. Compared to urokinase, we found that the fibrinolytic activity of the purified sFE was ~19,200 U/mL.</li>
	</ol>
	</li>
</ol>

Purifying a Fibrinolytic Enzyme from &lt;em&gt;Sipunculus nudus&lt;/em&gt; via Affinity Chromatography

<ol>
	<li>Rosell, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Patients+with+COVID-19+have+elevated+levels+of+circulating+extracellular+vesicle+tissue+factor+activity+that+is+associated+with+severity+and+mortality-brief+report.">Patients with COVID-19 have elevated levels of circulating extracellular vesicle tissue factor activity that is associated with severity and mortality-brief report.</a> Arteriosclerosis, Thrombosis, and Vascular Biology. 41 (2), 878-882 (2021).</li><li>Schultz, N. H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Thrombosis+and+thrombocytopenia+after+ChAdOx1+nCoV-19+vaccination.+The+New+England.">Thrombosis and thrombocytopenia after ChAdOx1 nCoV-19 vaccination. The New England.</a> Journal of Medicine. 384 (22), 2124-2130 (2021).</li><li>von Kaulla, K. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Urokinase-induced+fibrinolysis+of+human+standard+clots.">Urokinase-induced fibrinolysis of human standard clots.</a> Nature. 184 (4695), 1320-1321 (1959).</li><li>Van de Werf, F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Coronary+thrombolysis+with+tissue-type+plasminogen+activator+in+patients+with+evolving+myocardial+infarction.">Coronary thrombolysis with tissue-type plasminogen activator in patients with evolving myocardial infarction.</a> The New England Journal of Medicine. 310 (10), 609-613 (1984).</li><li>Schaller, J., Gerber, S. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+plasmin-antiplasmin+system:+structural+and+functional+aspects.">The plasmin-antiplasmin system: structural and functional aspects.</a> Cellular and Molecular Life Sciences. 68 (5), 785-801 (2011).</li><li>Ge, Y. -. H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+novel+antithrombotic+protease+from+marine+worm+Sipunculus+nudus.">A novel antithrombotic protease from marine worm Sipunculus nudus.</a> International Journal of Molecular Sciences. 19 (10), 3023 (2018).</li><li>Liu, X., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Purification+and+characterization+of+a+novel+fibrinolytic+enzyme+from+culture+supernatant+of+Pleurotus+ostreatus.">Purification and characterization of a novel fibrinolytic enzyme from culture supernatant of Pleurotus ostreatus.</a> Journal of Microbiology and Biotechnology. 24 (2), 245-253 (2014).</li><li>Choi, J. -. H., Sapkota, K., Kim, S., Kim, S. -. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Starase:+A+bi-functional+fibrinolytic+protease+from+hepatic+caeca+of+Asterina+pectinifera+displays+antithrombotic+potential.">Starase: A bi-functional fibrinolytic protease from hepatic caeca of Asterina pectinifera displays antithrombotic potential.</a> Biochimie. 105, 45-57 (2014).</li><li>Liu, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+novel+fibrinolytic+protein+From+Pheretima+vulgaris:+purification,+identification,+antithrombotic+evaluation,+and+mechanisms+investigation.">A novel fibrinolytic protein From Pheretima vulgaris: purification, identification, antithrombotic evaluation, and mechanisms investigation.</a> Frontiers in Molecular Biosciences. 8, 772419 (2022).</li><li>Wu, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Antioxidant,+hypolipidemic+and+hepatic+protective+activities+of+polysaccharides+from+Phascolosoma+esculenta.">Antioxidant, hypolipidemic and hepatic protective activities of polysaccharides from Phascolosoma esculenta.</a> Marine Drugs. 18 (3), 158 (2020).</li><li>. Preparation and application of natural fibrinolytic enzyme from peanut worm Available from: <a target="_blank" href="https://patents.google.com/patent/CN109295042A/en">https://patents.google.com/patent/CN109295042A/en</a> (2019)</li><li>Li, W., Yuan, M., Wu, Y., Xu, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Identification+of+genes+expressed+differentially+in+female+and+male+gametes+of+Sipunculus+nudus.">Identification of genes expressed differentially in female and male gametes of Sipunculus nudus.</a> Aquaculture Research. 51 (9), 3780-3789 (2020).</li><li>Ossipow, V., Laemmlii, U. K., Schibler, U. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+simple+method+to+renature+DNA-binding+proteins+separated+by+SDS-polyacrylamide+gel+electrophoresis.">A simple method to renature DNA-binding proteins separated by SDS-polyacrylamide gel electrophoresis.</a> Nucleic Acids Research. 21 (25), 6040-6041 (1993).</li><li>Hsu, T., Ning, Y., Gwo, J., Zeng, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=DNA+barcoding+reveals+cryptic+diversity+in+the+peanut+worm+Sipunculus+nudus.">DNA barcoding reveals cryptic diversity in the peanut worm Sipunculus nudus.</a> Molecular Ecology Resources. 13 (4), 596-606 (2013).</li><li>Abiko, Y., Iwamoto, M., Shimizu, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Plasminogen-plasmin+system.+I.+Purification+and+properties+of+human+plasminogen.">Plasminogen-plasmin system. I. Purification and properties of human plasminogen.</a> The Journal of Biochemistry. 64 (6), 743-750 (1968).</li><li>Abiko, Y., Iwamoto, M., Shimizu, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Plasminogen-plasmin+system.+II.+Purification+and+properties+of+human+plasmin.">Plasminogen-plasmin system. II. Purification and properties of human plasmin.</a> The Journal of Biochemistry. 64 (6), 751-757 (1968).</li><li>Wiman, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Affinity-chromatographic+purification+of+human+&#945;2-antiplasmin.">Affinity-chromatographic purification of human &#945;2-antiplasmin.</a> The Biochemical Journal. 191 (1), 229-232 (1980).</li><li>Sandbjerg Hansen, M., Clemmensen, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Partial+purification+and+characterization+of+a+new+fast-acting+plasmin+inhibitor+from+human+platelets.+Evidence+for+non-identity+with+the+known+plasma+proteinase+inhibitors.">Partial purification and characterization of a new fast-acting plasmin inhibitor from human platelets. Evidence for non-identity with the known plasma proteinase inhibitors.</a> The Biochemical Journal. 187 (1), 173-180 (1980).</li><li>Pietrocola, G., Rindi, S., Nobile, G., Speziale, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Purification+of+human+plasma/cellular+fibronectin+and+fibronectin+fragments.">Purification of human plasma/cellular fibronectin and fibronectin fragments.</a> Fibrosis. 1627, 309-324 (2017).</li><li>Nabiabad, H. S., Yaghoobi, M. M., Javaran, M. J., Hosseinkhani, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Expression+analysis+and+purification+of+human+recombinant+tissue+type+plasminogen+activator+(rt-PA)+from+transgenic+tobacco+plants.">Expression analysis and purification of human recombinant tissue type plasminogen activator (rt-PA) from transgenic tobacco plants.</a> Preparative Biochemistry and Biotechnology. 41 (2), 175-186 (2011).</li><li>Shearin, T. V., Pizzo, S. V., Gonzalez-Gronow, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Molecular+abnormalities+of+human+plasminogen+isolated+from+synovial+fluid+of+rheumatoid+arthritis+patients.">Molecular abnormalities of human plasminogen isolated from synovial fluid of rheumatoid arthritis patients.</a> Journal of Molecular Medicine. 75 (5), 378-385 (1997).</li></ol>

The authors have no conflicts of interest to disclose.

Due to the unavailability of the exact gene sequence of sFE, the currently used sFE was extracted from fresh S. nudus14. Moreover, the purification procedures of sFE reported in the literature were complicated and costly, as they were based on some general features of sFE, such as molecular weight, isoelectric point, ionic strength, and polarity15,16. No affinity purification protocol of sFE has been reported to date. In this stud...

Thrombosis is a major threat to public health, especially following the Covid-19 global pandemic1,2. Clinically, many plasminogen activators (PAs), such as tissue-type plasminogen activator (tPA) and urokinase (UK), have been widely used as thrombolytic drugs. PAs can activate patients&#39; plasminogen into active plasmin to degrade fibrin. Thus, their thrombolytic efficiency is heavily restricted by the patients&#39; plasminogen status3,4. Fibrinolytic agents, such as metalloproteinase plasmin and serine plasmin, are another type of clinical thrombolytic drug that also include fibrinolytic enzymes (FE) such as plasmin, which can dissolve clots directly but are quickly inactivated by various plasmin inhibitors5. Subsequently, a novel type of fibrinolytic agent has been reported that can dissolve the thrombus by not only activating the plasminogen into plasmin but also degrading the fibrin directly6-the fibrinolytic enzyme from the ancient peanut worm Sipunculus nudus (sFE)6. This bifunction endows sFE other advantages over traditional thrombolytic drugs, especially in terms of abnormal plasminogen status. Compared with other bifunctional fibrinolytic agents7,8,9, sFE displays several advantages, including safety, over non-food derived agents for drug development, especially for oral drugs. This is because the biosafety and biocompatibility of Sipunculus nudus have been well-established10.
Similar to the other natural fibrinolytic agents isolated from microorganisms, earthworms, and mushrooms, the purification of sFE from S. nudus is very complicated and includes multiple stages, such as tissue homogenization, ammonium sulphate precipitation, desalination, anion-exchange chromatography, hydrophobic interaction chromatography, and molecular sieving10,11,12. Such a purification system not only depends on proficient skills and expensive materials, but also requires several days to complete the whole procedure. Therefore, a simple purification program of sFE is of great significance for the further development of sFE. Fortunately, two crystals of sFE (PDB: 8HZP; PDB: 8HZO) have been successfully obtained (see Supplemental File 1 and Supplemental File 2). Through structural analysis and molecular docking experiments, we found that the catalytic core of sFE could specifically bind to targets containing arginine or lysine residues.
Herein, an affinity purification system was proposed for the first time, based on the crystal structure of sFE. By following this protocol, highly pure and highly active sFE could be purified from the crude extracts in a single affinity purification stage. The protocol developed here is not only important for the large scale preparation of sFE, but also may be applied for the purification of other fibrinolytic agents.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>30% Acrylamide-Bisacrylamide (29:1)</td>
			<td>Biosharp</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>2-Mercaptoethanol</td>
			<td>Solarbio</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Agarose G-10</td>
			<td>Biowest</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Ammonium persulfate</td>
			<td>SINOPHARM</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Ammonium sulfate</td>
			<td>SINOPHARM</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Arginine-Sepharose 4B</td>
			<td>Solarbio</td>
			<td>Arginine-agarose matrix</td>
			<td></td>
		</tr>
		<tr>
			<td>Bromoxylenol Blue (BPB)</td>
			<td>Solarbio</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Fast Silver Stain Kit</td>
			<td>Beyotime</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Fibrinogen</td>
			<td>Merck</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Glycine</td>
			<td>Solarbio</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Hydrochloric acid</td>
			<td>SINOPHARM</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Kinase</td>
			<td>RHAWN</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Lysine-Sepharose 4B</td>
			<td>Solarbio</td>
			<td>Lysine-agarose matrix</td>
			<td></td>
		</tr>
		<tr>
			<td>N,N,N&#39;,N&#39;-Tetramethylethylenediamine (TEMED)</td>
			<td>Sigma-Aldrich</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Prestained Color Protein Marker (10-170 kD)</td>
			<td>Beyotime</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium chloride</td>
			<td>SINOPHARM</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium Dodecyl Sulfonate (SDS)</td>
			<td>Sigma-Aldrich</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium hydroxide</td>
			<td>SINOPHARM</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Thrombin</td>
			<td>Meilunbio</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Tris(Hydroxymethyl) Aminomethane</td>
			<td>Solarbio</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Tris(Hydroxymethyl) Aminomethane Hydrochloride</td>
			<td>Solarbio</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Equipment</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>AKT Aprotein Purification System pure</td>
			<td>GE</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Automatic Vertical Pressure Steam Sterilizer MLS-3750</td>
			<td>SANYO</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Chemiluminescence Imaging System</td>
			<td>GE</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Constant Flow Pump BT-100</td>
			<td>QITE</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Constant Temperature Incubator</td>
			<td>JINGHONG</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Desktop Refrigerated Centrifuge 3-30KS</td>
			<td>SIGMA</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>DHG Series Heating and Drying Oven DGG-9140AD</td>
			<td>SENXIN</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Electric Glass Homogenizer DY89-II</td>
			<td>SCIENTZ</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Electronic Analytical Balance</td>
			<td>DENVER</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Electro-Thermostatic Water Bath DK-S12</td>
			<td>SENXIN</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Horizontal Decolorization Shaker</td>
			<td>Kylin-Bell</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Ice Machine AF 103</td>
			<td>Scotsman</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>KQ-500E Ultrasonic Cleaner</td>
			<td>ShuMei</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Magnetic Stirrer</td>
			<td>Zhi wei</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Micro Refrigerated Centrifuge H1650-W</td>
			<td>Cence</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Microwave Oven</td>
			<td>Galanz</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Milli-Q Reference</td>
			<td>Millipore</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Pipettor</td>
			<td>Thermo Fisher Scientific</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Precision Desktop pH Meter</td>
			<td>Sartorious</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Small-sized Vortex Oscillator</td>
			<td>Kylin-Bell</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Vertical Electrophoresis System</td>
			<td>Bio-Rad</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Consumable Material&#160;</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>200 &#181;L PCR Tube (200 &#181;L)</td>
			<td>Axygene</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Centrifuge Tube (1.5 mL)</td>
			<td>Biosharp</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Centrifuge Tube (5 mL)</td>
			<td>Biosharp</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Centrifuge Tube (50 mL)</td>
			<td>NEST</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Centrifuge Tube (7 mL)</td>
			<td>Biosharp</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Culture Dish (60 mm)</td>
			<td>NEST</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Filter Membrane (0.22 &#181;m)</td>
			<td>Millex GP</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Parafilm</td>
			<td>Bemis</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Pipette Tip (1 mL )</td>
			<td>KIRGEN</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Pipette Tip (10 &#181;L)</td>
			<td>Axygene</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Pipette Tip (200 &#181;L)</td>
			<td>Axygene</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Special Indicator Paper</td>
			<td>TZAKZY</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Ultra Centrifugal Filter Unit (15 mL 3 KDa)</td>
			<td>Millipore</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Ultra Centrifugal Filter Unit (4 mL 3 KDa)</td>
			<td>Millipore</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Universal pH Indicator</td>
			<td>SSS Reagent</td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

affinity purification of a fibrinolytic enzyme from sipunculus nudus

The fibrinolytic enzyme from Sipunculus nudus (sFE) is a novel fibrinolytic agent that can both activate plasminogen into plasmin and degrade fibrin directly, showing great advantages over traditional thrombolytic agents. However, due to the lack of structural information, all the purification programs for sFE are based on multistep chromatography purifications, which are too complicated and costly. Here, an affinity purification protocol of sFE is developed for the first time based on a crystal structure of sFE; it includes preparation of the crude sample and the lysine/arginine-agarose matrix affinity chromatography column, affinity purification, and characterization of the purified sFE. Following this protocol, a batch of sFE can be purified within 1 day. Moreover, the purity and activity of the purified sFE increases to 92% and&#160;19,200 U/mL,&#160;respectively. Thus, this is a simple, inexpensive, and efficient approach for sFE purification. The development of this protocol is of great significance for the further utilization of sFE and other similar agents.

Author Spotlight: Affinity Purification of a Fibrinolytic Enzyme from Sipunculus nudus  

Affinity Purification of a Fibrinolytic Enzyme from Sipunculus nudus

Our research is mainly about the purification of fibrinolytic enzyme. This work tries to establish a simple purification method for fibrinolytic enzyme. In this work, we report an arginine or lysine best-affinity purification system of fibrinolytic enzyme for the first time.Compared with the conventional purification methods, this is a simple, inexpensive, and efficient approach for the purification of fibrinolytic enzymes from Sipunculus nudus. The development of this protocol is of greater significance for the further utilization of fibrinolytic enzymes from Sipunculus nudus and other similar agents.

Following this protocol, crude tissue lysates were extracted, arginine-agarose matrix and lysine-agarose matrix affinity chromatography columns were built, purified sFE was obtained, and the purity and fibrinolytic activity of the purified sFE were measured by SDS-PAGE and fibrin plates, respectively.
After centrifugation, the collected supernatant was a transparent tan viscous liquid. Precipitation started when this supernatant was mixed with saturated ammonium sulfate solution (nine volumes)...

Watch this Scientific Journal Video about Affinity Purification of a Fibrinolytic Enzyme from Sipunculus nudus at JoVE.com

Here, we present an affinity purification method of a fibrinolytic enzyme from Sipunculus nudus that is simple, inexpensive, and efficient.

The fibrinolytic enzyme from Sipunculus nudus (sFE) is a novel fibrinolytic agent that can both activate plasminogen into plasmin and degrade fibrin ...

affinity-purification-of-a-fibrinolytic-enzyme-from-sipunculus-nudus

Research

JoVE Journal

Biochemistry

Protein Isolation from Sipunculus nudus

Protein Isolation from Sipunculus nudus  

Begin the sample treatment by dissecting 100 grams of fresh Sipunculus nudus and collecting their intestine and inner fluid.Add 300 milliliters of Tris hydrochloride buffer and homogenize at 1000 RPM for 60 seconds.Freeze thaw the homogenate three times.After centrifuging the freeze thawed homogenate, collect the supernatant and store it at 4

Affinity Chromatography Mediated Fibrinolytic Enzymes Purification from Crude Protein Extracts 

Filter the crude proteins extracted from the Sipunculus nudus intestine through a 0.22-micrometer filter membrane. Store this sample at four degrees Celsius for later use. Pack the arginine agarose matrix affinity chromatography column by loading the arginine agarose matrix medium into a five-milliliter empty chromatography column.Similarly, load the lysine agarose matrix affinity chromatography column by loading the lysine agarose matrix medium into an empty chromatography column. Equilibrate the affinity chromatography columns with double-distilled water followed by tris hydrochloride buffer. Load the filtered protein sample onto the pre-equilibrated column.Wash the column with five volumes of 0.02-molar tris hydrochloride buffer before eluting it with 0.15-0.25-0.35-0.45-0.55-and 0.65-molar sodium chloride solutions, successively. Once the elution peak appears in the 0.15-molar sodium chloride elution, collect the fractions in five-milliliter tubes. Concentrate the elution sample using a three-kilodalton ultracentrifugal filter and store this sample at minus 80 degrees Celsius for later use.When the protein solution was loaded onto the arginine agarose matrix affinity column, the flow-through peak appeared from approximately 40 to 66 minutes. In the gradient elution stage, elution with 0.15-molar sodium chloride peaked from approximately 94 to 110 minutes. When the protein solution was loaded to the lysine agarose matrix affinity column, the flow-through peak appeared from approximately 38 to 60 minutes.In the gradient elution stage, elution with 0.15-molar sodium chloride peaked from 80 to 86 minutes.

Fibrinolytic Activity of the Fibrinolytic Enzyme Purified from Sipunculus nudus

Fibrinolytic Activity of the Fibrinolytic Enzyme Purified from  Sipunculus nudus  

Begin the fibrin plate preparation by mixing 25 milligrams of fibrinogen with 1.25 milliliters of physiological saline. Next, prepare the thrombin solution by thoroughly mixing 100 units of thrombin with 1.05 milliliters of physiological saline. Then, prepare the agarose solution by adding 0.5 grams of agarose to 22.5 milliliters of 0.02 molar Tris-hydrochloride acid buffer.Heat the agarose solution at 100 degrees Celsius until it dissolves completely. Cool the agarose solution to around 50 degrees Celsius before adding the fibrinogen solution to it. Immediately add the thrombin solution, mix rapidly, and pour the mixture into a 60-millimeter culture dish.To load the sample, punch three-millimeter wells into the fibrin plates using a sterile Boer, and fill them with 10 microliters of samples. Incubate the plates at 37 degrees Celsius for 18 hours before measuring the size of their degrading zones and calculating the fibrinolytic activity. Fibrinolytic activity evaluation showed a 1.3-centimeter lysing zone in the urokinase control, no lysing zone in the physiological saline buffer, 2.1 centimeters of the lysing zone in the crude protein well, and 1.8 centimeters diameter of the lysing zone in the purified fibrinolytic enzyme well.

2.0K Views.  Huaqiao University.  Here, we present an affinity purification method of a fibrinolytic enzyme from Sipunculus nudus that is simple, inexpensive, and efficient.

Purifying a Fibrinolytic Enzyme from Sipunculus nudus via Affinity Chromatography

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