Plasminogen and plasmin

Thrombin (from bovine blood plasma) [9002-04-4] Mj 32,600 [EC 3.4.4.13]. Purified by chromatography on a DEAE-cellulose column, while eluting with O.IM NaCl, pH 7.0, followed by chromatography on Sephadex G-200. Final preparation was free from plasminogen and plasmin. [Yin and Wessler J Biol Chem 243 112 796S.]... 

MacLeod, T.J., Kwon, M., Filipenko, N.R., and D.M. Waisman, 2003, Phospholipid-associated annexin A2-S100A10 heterotetramer and its subunits characterization of the interaction with tissue plasminogen activator, plasminogen, and plasmin. J Biol Chem. 278(28) 25577—84. 

From the above, one can appreciate the complexities in designing a synthetic substrate assay for plasminogen and plasmin. Friberger has recommended certain guidelines in his recent review (F5). Most workers prefer SK over the other available activators. Latallo reported a total evaluation of the fibrinolytic system in patients (L7). This profile included the measurement of free plasmin activity and the concentration of plasminogen, its activators and inhibitors. A fully automated assay for plasminogens on a clinical analyzer has also been reported (PI). Comparison of the synthetic substrate... 

Plasmin is stable at an acid pH (2.3) but is rapidly autodigested at a neutral pH. The exact molecular weights of plasmin and plasminogen are unknown they have been estimated to range between 108,000 and 127,000. Both plasminogen and plasmin are suspected to be glycoproteins (containing approximately 1.0-1.5% hexose). The amino acid composition of the proteins has not been established. 

Robbins, K.C., Bernabe, P., Arzadon, L., Summaria, L. NH2-terminal sequences of mammalian plasminogens and plasmin S-carboxymethyl heavy (A) and light (B) chain derivatives a reevaluation of the mechanism of activation of plasminogen. J. biol. Chem. 248, 7242-7246 (1973)... 

Fibrinolytics. Figure 3 Plasminogen activation (a) Kinetics of plasminogen activation by uPA (urokinase-type) and tPA (tissue-type) plasminogen activators. Effect of fibrin (b) Ternary complex formation between enzyme (tPA), substrate (Pg) and cofactor (F) Abbreviations plasmin (P), fibrin (F), plasminogen (Pg). Plasmin, formed in time, is expressed in arbitrary units. 

Although the exact action of the thrombolytic dragp is slightly different, these drugs break down fibrin clots by converting plasminogen to plasmin (fibrinolysin). Plasmin is an enzyme that breaks down the fibrin of a blood clot. This reopens blood vessels after their occlusion and prevents tissue necrosis. 

Co-enzyme obtained from cultures of various strains of Streptococcus haemolyticus and capable of changing plasminogen into plasmin (complex enzyme mixture of streptokinase, streptodornase and streptolysin 0"). From fermentation liquors of hemolytic streptococci species Streptococcus haemolyticus), e. g. H 46 A. 

Figure 51-7. Scheme of sites of action of streptokinase, tissue plasminogen activator (t-PA), urokinase, plasminogen activator inhibitor, and Kj-antiplasmin (the last two proteins exert inhibitory actions). Streptokinase forms a complex with plasminogen, which exhibits proteolytic activity this cleaves some plasminogen to plasmin, initiating fibrinolysis. 

Lucas M. A., Fretto L. S., McKee P. A. The relationship of fibrinogen structure to plasminogen activation and plasmin activity during fibrinolysis. Ann N Y Acad Sci 1983 408, 71-91. 

Plasmin does not occur in free form but is generated as needed from an inactive precursor, plasminogen. The active of plasminogen to plasmin is a proteolytic event and can be inhibited by ut-... 

Urokinase is a serine protease produced by the kidney and is found in both the plasma and urine. It is capable of proteolytically converting plasminogen into plasmin. Two variants of the enzyme have been isolated a 54 kDa species and a lower molecular mass (33 kDa) variant. The lower molecular mass form appears to be derived from the higher molecular mass moiety by proteolytic processing. Both forms exhibit enzymatic activity against plasminogen. 

---