plasmin

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A proteolytic enzyme that is formed from plasminogen in blood plasma and dissolves the fibrin in blood clots. Also called fibrinolysin.

A proteolytic enzyme which can digest many proteins through the process of hydrolysis. Plasmin (fibrinolysin) is found in plasma in the form of the inert precursor, or zymogen, plasminogen (profibrinolysin); its site of synthesis in the body is unknown. Plasma also contains several inhibitors which limit the action of plasmin.

Plasma itself has the potentiality of activating plasminogen, perhaps because it contains intrinsic activators. Plasmin activator is produced in blood vessel walls, from which it is released following vascular injury. Further, the process of blood coagulation may foster the activation of plasminogen. Moreover, the presence of a fibrin clot enhances activation of plasminogen by many agents, perhaps because plasminogen is adsorbed to the fibrin and thus separated from its inhibitors in the plasma.

Plasmin can act on many protein substrates. It liquefies coagulated blood by digesting fibrin (fibrinolysis), the insoluble meshwork of the clot; it also digests fibrinogen, the precursor of fibrin, rendering it incoagulable. The digestion products of fibrinogen and fibrin are anticoagulant substances which further interfere with the clotting process. Plasmin also inactivates several other protein procoagulant factors, particularly proaccelerin (factor V) and antihemophilic factor (factor VIII). Other substrates attacked by plasmin include gamma globulin and several protein or polypeptide hormones found in plasma.

The action of plasmin may be related to certain body defenses. It can convert the first component of complement to a proteolytic enzyme. It can also liberate polypeptide kinins (for example, bradykinin) from plasma precursors. The kinins can reproduce such elements of the inflammatory process as pain, dilatation and increased permeability of small blood vessels, and the migration of leukocytes. Besides these physiological actions, plasmin also hydrolyzes casein, gelatin, denatured hemoglobin, and certain synthetic esters of arginine and lysine, for example, p-toluenesulfonylarginine methyl ester (TAME). See also Blood; Complement; Fibrinogen; Immunology; Inflammation.

Collective term for one or more proteolytic enzymes found in the blood. The proteolytic enzymes are capable of digesting fibrin, fibrinogen, and proaccelerin. Plasminogen, the inactive form, may become active spontaneously in shed blood. An activator, fibrinokinase (fibrinolysokinase), is found in many animal tissues. Also called fibrinolysin, lysin, plasma proteolytic enzyme, and tryptase.

An enzyme found in the blood which catalyses the breakdown of fibrin clots.

The active principle of the fibrinolytic or clot-lysing system, a proteolytic enzyme formed from plasminogen which hydrolyzes fibrin, fibrinogen, factor V and other proteins. It has the particular ability to dissolve formed fibrin clots. Called also fibrinolysin.

• p. inhibitors — include α₂-macroglobulin, α₁-antitrypsin, C1-inactivator, antithrombin III.

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Plasminogen
PDB rendering based on 1b2i.
Available structures: 1b2i, 1bml, 1bui, 1cea, 1ceb, 1ddj, 1hpj, 1hpk, 1i5k, 1ki0, 1krn, 1l4d, 1l4z, 1pk4, 1pkr, 1pmk, 1qrz, 1rjx, 2doh, 2doi, 2pk4, 5hpg
Identifiers
Symbols	PLG; DKFZp779M0222
External IDs	OMIM: 173350 MGI: 97620 HomoloGene: 55452
EC number	3.4.21.7
Gene ontology Molecular function: • plasmin activity • calcium ion binding • protein binding • peptidase activity Cellular component: • extracellular space Biological process: • proteolysis • apoptosis • induction of apoptosis • blood coagulation • negative regulation of cell proliferation • negative regulation of angiogenesis • tissue regeneration • fibrinolysis • negative regulation of blood vessel endothelial cell migration • myoblast differentiation • muscle maintenance
RNA expression pattern
More reference expression data
Orthologs
	Human	Mouse
Entrez	5340	18815
Ensembl	ENSG00000122194	ENSMUSG00000059481
Uniprot	P00747	Q3V1T9
Refseq	NM_000301 (mRNA) NP_000292 (protein)	NM_008877 (mRNA) NP_032903 (protein)
Location	Chr 6: 161.04 - 161.09 Mb	Chr 17: 12.22 - 12.26 Mb
Pubmed search	[1]	[2]

Plasmin is an important enzyme (EC 3.4.21.7) present in blood that degrades many blood plasma proteins, most notable, fibrin clots. The degradation of fibrin is termed fibrinolysis. In humans, the plasmin protein is encoded by the PLG gene.^[1]

Contents 1 Function 2 Pathology 3 References 4 Further reading 5 External links

Function

Plasminogen (PLG) is a circulating zymogen that is converted to the active enzyme plasmin by cleavage of the peptide bond between Arg-560 and Val-561, which is mediated by urokinase and tissue plasminogen activator. The main function of plasmin is to dissolve fibrin blood clots. Plasmin, like trypsin, belongs to the family of serine proteases.^[1][2][3]

Plasmin is a serine protease that is released as plasminogen from the liver into the circulation and activated by tissue plasminogen activator (tPA), urokinase plasminogen activator (uPA), and factor XII (Hageman factor). Fibrin is a cofactor for plasminogen activation by tissue plasminogen activator. Urokinase plasminogen activator receptor (uPAR) is a cofactor for plasminogen activation by urokinase plasminogen activator. Plasmin is inactivated by alpha 2-antiplasmin, a serine protease inhibitor (serpin).

Apart from fibrinolysis, plasmin proteolyses proteins in various other systems: It activates collagenases, some mediators of the complement system and weakens the wall of the Graafian follicle (leading to ovulation). It cleaves fibrin, fibronectin, thrombospondin, laminin, and von Willebrand factor.

Apart from fibrinolysis, plasminogen is shown to play important role in wound healing, liver repair as well as the mantainance of liver homeostasis.

Pathology

Deficiency in plasmin may lead to thrombosis, as clots are not degraded adequately. Plasminogen deficiency in mice leads to defective wound healing, defective liver repair, reproductive abnormalities.^{[citation needed]}

References

1. ^ ^{a b} "Entrez Gene: plasminogen". http://www.ncbi.nlm.nih.gov/sites/entrez?Db=gene&Cmd=ShowDetailView&TermToSearch=5340. 
2. ^ Miyata T, Iwanaga S, Sakata Y, Aoki N (October 1982). "Plasminogen Tochigi: inactive plasmin resulting from replacement of alanine-600 by threonine in the active site". Proc. Natl. Acad. Sci. U.S.A. 79 (20): 6132–6. doi:10.1073/pnas.79.20.6132. PMID 6216475. PMC: 347073. http://www.pnas.org/cgi/pmidlookup?view=long&pmid=6216475. 
3. ^ Forsgren M, Råden B, Israelsson M, Larsson K, Hedén LO (March 1987). "Molecular cloning and characterization of a full-length cDNA clone for human plasminogen". FEBS Lett. 213 (2): 254–60. doi:10.1016/0014-5793(87)81501-6. http://linkinghub.elsevier.com/retrieve/pii/0014-5793(87)81501-6. 

Further reading

• Shanmukhappa K, Mourya R, Sabla GE, Degen JL, Bezerra JA (July 2005). "Hepatic to pancreatic switch defines a role for hemostatic factors in cellular plasticity in mice". Proc. Natl. Acad. Sci. U.S.A. 102 (29): 10182–7. doi:10.1073/pnas.0501691102. PMID 16006527. 
• Anglés-Cano E, Rojas G (2003). "Apolipoprotein(a): structure-function relationship at the lysine-binding site and plasminogen activator cleavage site". Biol. Chem. 383 (1): 93–9. doi:10.1515/BC.2002.009. PMID 11928826. 
• Ranson M, Andronicos NM (2004). "Plasminogen binding and cancer: promises and pitfalls". Front. Biosci. 8: s294–304. doi:10.2741/1044. PMID 12700073. 

External links

• MeSH Plasmin

This article incorporates text from the United States National Library of Medicine, which is in the public domain.

v • d • e Proteins: globulins Serum Alpha globulins serpins: Alpha 1-antichymotrypsin · Alpha 1-antitrypsin · Alpha 2-antiplasmin · Antithrombin (Heparin cofactor II) carrier proteins: Retinol binding protein · Transcortin · Ceruloplasmin other: alpha-2-Macroglobulin · Haptoglobin · Orosomucoid Beta globulins carrier proteins: Sex hormone-binding globulin · Transferrin other: Angiostatin · Haemopexin · Beta-2 microglobulin · Factor H · Plasminogen · Properdin Gamma globulin Immunoglobulins Other Fibronectin · Macroglobulin/Microglobulin · Transcobalamin Other Beta-lactoglobulin (Lactoferrin) · Thyroglobulin · Alpha-lactalbumin

v • d • e Proteins: coagulation Coagulation factors Primary hemostasis vWF platelet membrane glycoproteins: Ib (A, B, IX) · IIb/IIIa (IIb, IIIa) · VI Intrinsic pathway HMWK/Bradykinin · Prekallikrein/Kallikrein · XII "Hageman" XI · IX · VIII Extrinsic pathway III "Tissue factor" · VII Common pathway X · V · II "(Pro)thrombin" · I "Fibrin" XIII Coagulation inhibitors Antithrombin (inhibits II, IX, X, XI, XII) · Protein C (inhibits V, VIII)/Protein S (cofactor for protein C) · Protein Z (inhibits X) · ZPI (inhibits X, XI) · TFPI (inhibits III) Thrombolysis/fibrinolysis Plasmin · tPA/urokinase · PAI-1/2 · α2-AP · α2-macroglobulin · TAFI

v • d • e Endopeptidases: serine proteases/serine endopeptidases (EC 3.4.21) Digestive enzymes Enteropeptidase · Trypsin · Chymotrypsin · Elastase (Neutrophil, Pancreatic) Coagulation factors: Thrombin · Factor VIIa · Factor IXa · Factor Xa · Factor XIa · Factor XIIa · Kallikrein (PSA, KLK1, KLK2, KLK3, KLK4, KLK5, KLK6, KLK7, KLK8, KLK9, KLK10, KLK11, KLK12, KLK13, KLK14, KLK15) fibrinolysis: Plasmin · Plasminogen activator (Tissue plasminogen activator · Urinary plasminogen activator) Complement system Factor B · Factor D · Factor I · MASP (MASP1, MASP2) · C3-convertase Other immune system Chymase · Granzyme · Tryptase · Proteinase 3/Myeloblastin Venombin Ancrod · Batroxobin Other Acrosin · Prolyl endopeptidase · Pronase · Proprotein convertases (1, 2) · Reelin · Subtilisin/Furin · Streptokinase · S1P · Cathepsin (A, G)

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