Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.21.7 (plasmin)
 9,023 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effect of plasmin on the subunit polypeptides of factor XIII has been investigated. purified human plasma (a2b2) and platelet (a2) zymogens and the enzyme (a2) were incubated with plasmin at plasmin: factor XIII ratios of 0.03-0.5 casein units per mg protein. Under conditions in which plasmin readily digested fibrinogen and casein, it had no effect on either a2b2 or a2. There was no evidence for cleavage of peptide bonds in the zymogens, and all the potential catalytic activity was retained after prolonged incubation. Similarly a2*, either in the presence or absence of b subunit, was also unaffected by plasmin incubation. 90% of the activity was recovered after incubation of factor XIII with plasmin. b subunit was also not degraded. Additionally, no evidence was obtained that plasmin could activate factor Xiii. These results indicate that in purified systems there is no significant interaction between plasmin and factor XIII.
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PMID:Resistance of factor XIII to degradation or activation by plasmin. 645 19

A controlled digestion of native human plasminogen (Glu1-plasminogen) from either carbohydrate variant 1 or 2 with pancreatic elastase yields, among others, an activatable fragment, designated Val354-plasminogen (Pgc). This species represents the smallest human plasminogen fragment (ca., 50,000 Mw) known to bind to Sepharose-lysine. Pgc forms a tight equimolar complex with streptokinase, as determined by sucrose density ultracentrifugation, whether formed from Val354-plasminogen or Val354-plasmin. The Val354-plasmin-streptokinase complex readily activates ovine plasminogen, which is normally insensitive to streptokinase, and this complex is essentially inactive toward casein, similar to the equimolar complexes formed with Lys77-plasmin and the elastase fragment, Val442-plasmin.
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PMID:Complex formation of human Val354-plasminogen with streptokinase. 668 32

The virulence of Pseudomonas aeruginosa, which is easily differentiated from the two other most common pseudomonad pathogens, is low. This species primarily causes disease in patients with local anatomic changes or in the immune compromized hosts. A number of bacterial factors are involved in the pathogenesis of the microbe. Surface structures like the glycocalyx-capsular material-is involved in attachment to mucosal surfaces and resistance against phagocytosis and immunolysis of cells. The interference with bacterial components on mucociliar clearance of the bronchial tract have been described. In cystic fibrosis local environmental substances enhancing the production of capsular material have been described and the tendency for colonization of mucoid strains in cystic fibrosis probably is related to these factors. Another general component of gram-negative bacteria is endotoxin, but the toxicity of this cell wall constituent is relatively low in P. aeruginosa. A number of proteolytic enzymes with a probable role in disease have been described: collagenase, fibrinolysin, elastase, caseinase, and gelatinase. A proteolytic enzyme with activity against substances like casein, egg albumin, gluten, and haemoglobin has been described. A component like exotoxin A can produce skin lesions and antibodies produced with toxoid of exotoxin A are protective against this bacterial agent. Enterotoxin has been described based on rabbit intestinal loop preparations, but has not been further characterized and diarrhoea is rarely caused by P. aeruginosa. Haemolytic effect has been caused by a heat labile phospholipase C and by a heat stabile moiety. A leucocidin has been described: this may in part be capsular material. In addition, an exoenzyme S has been suggested as a virulence factor.
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PMID:Pathogenetic factors of Pseudomonas aeruginosa. 679 59

Conditions are developed for determining potential activity of plasminogen in amine groups formed in casein hydrolysis. Two variants of determination are suggested: by means of a ninhydrin reagent and trinitrobenzene sulphoacid. The method permits determining 0.02-0.1 of plasmin casein units (cas. units); it is 20 times as sensitive as the known caseinolytic method based on determination of the degree of tyrosine absorption.
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PMID:[Micromethod for plasminogen determination]. 732 97

The activation of plasminogen by macrophage is regulated by their expression of receptors for urokinase and plasmin(ogen). In these studies we have examined plasmin(ogen) binding to adherent human THP-1 macrophage. Plasmin bound to the THP-1 cells in a time- and dose-dependent manner (Kd 15.8 +/- 6.2 nM; Bmax 1.4 +/- 0.3 x 10(6)/cell). The lysine analog epsilon-aminocaproic acid competitively inhibited plasmin binding. The fraction of membrane-bound plasmin, however, became increasingly resistant to displacement with epsilon-aminocaproic acid. Over a 24-h period, membrane-bound plasmin activity fell 80% despite the presence of catalytically active plasmin in the incubation media. The loss of receptor-bound plasmin activity was not due to proteolytic alterations of its receptor since 125I-Lys-plasminogen bound to THP-1 cells pretreated with plasmin with similar affinity as to untreated cells. Following a 24-h incubation of 125I-Lys-plasminogen or 125I-plasmin with THP-1 cells, several degradative fragments were apparent in their conditioned media. The smaller degradative fragments (28 and 36 kDa) lacked cell binding activity and were demonstrated to be active by casein-zymography. A 48-kDa fragment bound to cells in a lysine-dependent manner but was not active. In contrast, phenylmethylsulfonyl fluoride-inactivated 125I-plasmin retained its binding activity over 24 h, and degradative fragments were not present in the conditioned media. The binding of 125I-Lys-plasmin(ogen) to THP-1 cells was also examined in the presence of excess alpha 2 plasmin inhibitor. Despite the absence of fluid-phase plasmin activity, membrane-bound 125I-Lys-plasmin(ogen) decreased over 24 h. At 24 h a radiolabeled 48-kDa fragment was observed in the conditioned media and together with 125I-Lys-plasmin(ogen) was bound to cells. Unlike 125I-Lys-plasmin, the 48-kDa fragment did not form a complex with alpha 2 plasmin inhibitor. Thus, autoproteolysis of receptor-bound plasmin results in fragments with truncated physiologic properties that possess either cell binding or catalytic activities. We propose that autoproteolysis is a mechanism for regulating membrane-bound plasmin activity.
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PMID:Regulation of macrophage receptor-bound plasmin by autoproteolysis. 752 19

Incubation of washed platelets in Tyrode buffer, pH 7.5, with insulin (200 microU/ml) and CaCl2 (1.2 mM) at 37 degrees C for 3 h resulted in a threefold increase of plasminogen activator activity in the supernatant over the basal level as determined by both the amidolytic assay and the proteolysis of alpha-casein through the formation of plasmin from plasminogen. This plasminogen activator showed no plasmin-like activity and was inhibited by anti-tissue plasminogen activator antibody as well as by type 1 plasminogen activator inhibitor. The substrate specificity and the inhibition of the enzymic activity by various inhibitors indicated that the platelet plasminogen activator (pPA) was related to tissue-type plasminogen activator of relative molecular weight 56,000. Fibrinolytic activity of pPA and its insulin-dependent release were demonstrated by the shortening of euglobulin lysis time and by the clot lysis time of platelet-rich plasma from normal and type I diabetes mellitus patients. Treatment of platelet membranes with insulin also increased the release of pPA. Increased levels of adenosine 3',5'-cyclic monophosphate (cAMP) in platelets by incubation with various agents completely inhibited the insulin-induced release of the activator. On the other hand, inhibition of platelet aggregation by aspirin had no effect on the release of pPA, indicating that the effect of cAMP was not due to the inhibition of platelet aggregation by the nucleotide.
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PMID:Insulin-induced release of plasminogen activator from human blood platelets. 753 Sep 14

Serine proteinase inhibitors play major roles in physiological and pathophysiological processes such as angiogenesis, intravascular fibrinolysis, wound healing, and tumor invasion, and metastasis. Here, we report that human umbilical vein endothelial cells (HUVEC) synthesize three inhibitors (33,000, 31,000, and 27,000 Da) which inhibit degradation of gelatin or casein by trypsin, elastase, plasmin, and alpha-chymotrypsin. The 33- and 31-kDa inhibitors were constitutively found in the cell lysate and extracellular matrix, but not in the conditioned medium of HUVEC. Following treatment with phorbol 12-myristate-13-acetate (PMA), all the three inhibitors were expressed in the CM and increased activity was found in cell lysates and extracellular matrix. The inhibitors were not detected in PMA-treated cells in the presence of cycloheximide or actinomycin D. The inhibitors specifically bound to trypsin and were recovered from trypsin affinity column as smaller-sized inhibitors without loss of antitrypsin activity. Polyclonal antibodies to inter-alpha-trypsin inhibitor did not cross-react with the 33-, 31-, and 27-kDa inhibitors. These results suggest that HUVEC synthesize and secrete novel 33-, 31-, and 27-kDa serine proteinase inhibitors.
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PMID:Partial characterization of novel serine proteinase inhibitors from human umbilical vein endothelial cells. 753 5

Five British Saanen goats were milk sampled during the first 39 weeks of lactation to determine changes in casein composition. Caseins were separated by anion- and cation-exchange FPLC to determine the relative amounts of the individual caseins. Acid, alkaline and SDS-PAGE were used to determine possible genetic polymorphisms and observe any lactational changes. Total casein nitrogen was determined using a micro-Kjeldahl method and this allowed the concentrations of individual caseins to be calculated. The milk of one animal, which had the deduced genotype alpha s1-CnAB, showed higher concentrations of both total and alpha s1-casein. The remainder of the group were either heterozygous alpha s1-CnBE or, more probably, homozygous alpha s1-CnE and produced milk of a generally lower protein concentration. Both FPLC and PAGE results showed that the relative amounts and concentrations of alpha s2-casein decreased with stage of lactation, consistent with its susceptibility to proteolysis. The relative amounts of the breakdown products of plasmin attack on beta-casein, gamma-caseins, were highly negatively correlated with milk yield (r = -0.942, P < 0.001) in the declining phase of lactation, reflecting the gradual involution of the gland at this time. The relative amount of kappa-casein increased by approximately 50% after peak lactation and its concentration almost doubled near the end of lactation. These compositional changes may alter the processing qualities of goats' milk in relation to cheese production.
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PMID:Changes in casein composition of goats' milk during the course of lactation: physiological inferences and technological implications. 759 29

The whole N fraction of six samples of hard and semi-hard pressed cheeses was analysed using PAGE, polyacrylamide gel isoelectric focusing and immunoblotting with polyclonal antibodies against beta- and alpha s1-casein. The origin of some electrophoretic bands corresponding to peptides produced from the enzymic degradation of the casein fractions was established. A number of these peptides were also present in the in vitro hydrolysates of casein with plasmin and chymosin. Thus, it was also possible to determine which casein was the source of each peptide and which enzymes were active in cheese. Compared with the traditional Coomassie staining procedures, immunoblotting is more sensitive and specific, making the interpretation of each electrophoretic profile easy. Thus, it was also possible to obtain a clear picture of the state of each casein fraction in a cheese variety. Two main peptides were isolated from the pH 4.6-insoluble N fraction of Parmigiano-Reggiano using DEAE-cellulose chromatography and identified, from the amino acid sequence of the N- and C-terminal ends, as gamma 3-casein (beta-casein(f108-209)) and alpha s1-PL1 (alpha s1-casein(f80-199). In both cases, a Lys-X bond was hydrolysed, indicating the action of a trypsin-like enzyme in beta- and alpha s1-casein hydrolysis during the ripening of this variety of hard pressed cheese.
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PMID:Gel electrophoresis and immunoblotting for the detection of casein proteolysis in cheese. 760 74

Eighty-six samples of quarter milk from 31 cows, the mean SCC of which exceeded 400,000 cells/ml, were analyzed for SCC, chloride content, pH, clotting time, total N, soluble N, casein N, proteose-peptone content, plasmin activity, and amount of free NH2 groups, parameters that are related to the udder health condition and to the deterioration of the protein quality. Analysis of the milk from each quarter separately improved the correlations considerably compared with analyses of samples from all 4 quarters mixed together. Measurement of free NH2 groups, using the 2, 4, 6-trinitrobenzene sulfonic acid, was not appropriate for estimating the extent of protein deterioration in milk samples with different SCC. Unlike SCC, the proteolysis index, plasmin activity, and the proteose-peptone content were highly correlated themselves and with most of the parameters related to proteolysis in milk. Proteolysis occurred in milk samples with SCC as low as 250,000 cells/ml. The quality of milk protein decreased unavoidably during lactation, regardless of SCC.
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PMID:Proteolysis in samples of quarter milk with varying somatic cell counts. 1. Comparison of some indicators of endogenous proteolysis in milk. 767 17


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