Name: Affinity Purification of a Fibrinolytic Enzyme from Sipunculus nudus (Video) | JoVE
Uploaded: 2023-06-02T12:10:00
Description: Watch this Scientific Journal Video about Affinity Purification of a Fibrinolytic Enzyme from Sipunculus nudus at JoVE.com

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 ...

Purifying a Fibrinolytic Enzyme from Sipunculus nudus 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>

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.

Affinity Purification of a Fibrinolytic Enzyme from Sipunculus nudus

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

Affinity Purification of a Fibrinolytic Enzyme from Sipunculus nudus (Video) | JoVE 

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 ...