Reversible and Irreversible Alterations of Human Plasminogen Indicated by Changes in Susceptibility to Plasminogen Activators and in Response to ∈-Aminocaproic Acid

1974 ◽  
Vol 32 (02/03) ◽  
pp. 325-340 ◽  
Author(s):  
Sixtus Thorsen ◽  
Preben Kok ◽  
Tage Astrup
Keyword(s):  
Ionic Strength ◽  
Aminocaproic Acid ◽  
Plasminogen Activators ◽  
Plasminogen Activation ◽  
Porcine Tissue ◽  
Biphasic Pattern ◽  
Tissue Plasminogen ◽  
Human Plasminogen ◽  
Uniform Manner ◽  
Low Ionic Strength

SummaryIncreasing concentrations of EACA produce a biphasic pattern of inhibition and enhancement of urokinase-induced lysis of bovine fibrin containing bovine plasminogen, while the inhibition of fibrinolysis induced by a porcine tissue plasminogen activator increases uniformly. The biphasic EACA pattern is also observed with human plasminogen in fibrinolytic and caseinolytic assays of urokinase. The biphasic EACA pattern produced with urokinase is related to the presence of a genuine form of plasminogen. The enhancement phase is caused by an increased rate of plasminogen activation in the presence of EACA. A brief treatment of genuine plasminogen with acid at ionic strength 0.15 results in an enhanced susceptibility to plasminogen activators and in a partial abolishment of the biphasic response. These acid-induced alterations of plasminogen seem to be reversed by acid dialysis at low ionic strength. Other preparations of plasminogen with enhanced susceptibility to activators have lost the ability to produce a biphasic pattern of inhibition and enhancement of urokinase-induced plasminogen activation in the presence of EACA and this ability does not return after acid dialysis at low ionic strength. EACA inhibits all plasmin preparations, whether prepared from genuine or altered forms of plasminogen, in the same uniform manner.Our results show that different forms of plasminogen can be identified by differences in the susceptibilities to activators, by their response to EACA, and by the reversibility or irreversibility of the alterations.

scholarly journals The fibrinolytic system enables the onset of Plasmodium infection in the mosquito vector and the mammalian host

2021 ◽  
Vol 7 (6) ◽  
pp. eabe3362 ◽  
Author(s):  
Thiago Luiz Alves e Silva ◽  
Andrea Radtke ◽  
Amanda Balaban ◽  
Tales Vicari Pascini ◽  
Zarna Rajeshkumar Pala ◽  
...  
Keyword(s):  
Plasminogen Activators ◽  
Fibrinolytic System ◽  
Matrix Proteins ◽  
Parasite Development ◽  
Mammalian Host ◽  
Mosquito Vector ◽  
Plasminogen Activation ◽  
Plasmodium Infection ◽  
Human Plasminogen ◽  
Vertebrate Hosts

Plasmodium parasites must migrate across proteinaceous matrices to infect the mosquito and vertebrate hosts. Plasmin, a mammalian serine protease, degrades extracellular matrix proteins allowing cell migration through tissues. We report that Plasmodium gametes recruit human plasminogen to their surface where it is processed into plasmin by corecruited plasminogen activators. Inhibition of plasminogen activation arrests parasite development early during sexual reproduction, before ookinete formation. We show that increased fibrinogen and fibrin in the blood bolus, which are natural substrates of plasmin, inversely correlate with parasite infectivity of the mosquito. Furthermore, we show that sporozoites, the parasite form transmitted by the mosquito to humans, also bind plasminogen and plasminogen activators on their surface, where plasminogen is activated into plasmin. Surface-bound plasmin promotes sporozoite transmission by facilitating parasite migration across the extracellular matrices of the dermis and of the liver. The fibrinolytic system is a potential target to hamper Plasmodium transmission.

Preparation of Human Plasminogen Suitable as Substrate for Quantitative Determination of Plasminogen Activators

1966 ◽  
Vol 15 (03/04) ◽  
pp. 511-518
Author(s):  
W Berg ◽  
K Korsan-Bengtsen ◽  
J Ygge
Keyword(s):  
Ionic Strength ◽  
Quantitative Determination ◽  
Spontaneous Activity ◽  
Human Plasma ◽  
Gel Filtration ◽  
Plasminogen Activators ◽  
Simple Method ◽  
Neutral Ph ◽  
Human Plasminogen

SummaryA simple method for preparation of plasminogen with low spontaneous activity and soluble at a neutral pH and at physiological ionic strength is described. Euglobulin made from fresh, oxalated, BaSO4-adsorbed, human plasma was first purified by means of gel filtration on Sephadex G-200. After gel filtration, further purification and concentration was done on DEAE-sephadex A-50. The activity was 100-130 casein units per mg tyrosine.

Kinetics Of Plasminogen Activation By Tissue Plasminogen Activator. Role Of Fibrin

1981 ◽  
Author(s):  
M Hoylaerts ◽  
D C Rijken ◽  
H R Lijnen ◽  
D Collen
Keyword(s):  
Plasminogen Activator ◽  
Tissue Plasminogen Activator ◽  
Catalytic Efficiency ◽  
Reaction Scheme ◽  
Plasminogen Activation ◽  
Catalytic Rate Constant ◽  
Activation Rate ◽  
Tissue Plasminogen ◽  
Human Plasminogen ◽  
Straight Lines

The activation of human plasminogen (P) by two-chain tissue plasminogen activator (A) was studied in the presence of fibrin films (F) of increasing size and surface density. Initial rates of plasminogen activation (v) were determined as a function both of the plasminogen and fibrin concentration. The activation rate was strongly dependent on the presence of fibrin and plots of 1/v versus 1/ [p] or 1 /[F] yielded straight lines. The kinetic data were in agreement with the following reaction scheme.According to this model tissue plasminogen activator would bind to fibrin with a dissociation constant (KF of 0.2 µM and this complex fixes plasminogen with a Michaelis constant (Kp’) of 0.15 µM (Glu-plasminogen) or 0.02 µM (Lys-plasminogen) to form a ternary complex, converted to plasmin with a catalytic rate constant kcat = 0.05 s-1. This mechanism implies that both plasminogen and tissue plasminogen activator are concentrated on the fibrin surface through formation of a fibrin bridge. Activation of plasminogen in the absence of fibrin occurs with Km = 65 µM (Glu-plasminogen) or Km= 19 µM (Lys-plasminogen) and kcat = 0.05 s-1. Our data suggest that fibrin enhances the activation rate of plasminogen by tissue plasminogen activator by increasing the affinity of plasminogen for fibrin-bound tissue plasminogen activator and not by influencing the catalytic efficiency of the enzµMe. These data also support the hypothesis that fibrinolysis is both triggered by and directed towards fibrin.Generated plasmin was quantitated by measuring the rate of solubilization of 125I-labeled fibrin.

Differentiation between Plasminogen Activators by Means of Epsilon- Aminocaproic Acid

1972 ◽  
Vol 27 (01) ◽  
pp. 077-087 ◽  
Author(s):  
P Kok ◽  
T Astrup
Keyword(s):  
Plasminogen Activator ◽  
Human Urine ◽  
Aminocaproic Acid ◽  
Plasminogen Activators ◽  
Uterine Tissue ◽  
Biphasic Pattern ◽  
Fibrin Plate ◽  
Epsilon Aminocaproic Acid ◽  
Millimolar Concentration

SummaryThe differentiation between plasminogen activators from tissue and urine by means of the patterns of inhibition produced by epsilon-aminocaproic acid (EACA) in fibrin plate assays was investigated. Different inhibition patterns reflected genuine differences between two types of activators. The method allows the differentiation between two types of activators in weakly fibrinolytic and impure activator solutions.A biphasic pattern of inhibition by EACA was observed with human urine as well as with the purified urokinase preparations. The degree of enhancement of fibrinolysis observed in the millimolar concentration range of EACA fluctuated with the fibrin substrate and was, in part, related to its plasminogen content. Increasing concentrations of EACA produced a uniformly increasing inhibition of preparations of tissue activator obtained in various degrees of purity from porcine ovary and heart. Plasmin was uniformly inhibited by EACA. Inhibition of plasmin required about 100 times higher concentrations of EACA than inhibition of tissue activator-induced fibrinolysis. EACA produced a slightly biphasic pattern of inhibition with plasminogen activator from human uterine tissue.

Enhancement of Tissue Plasminogen Activator-Catalyzed Plasminogen Activation by Escherichia coii S Fimbriae Associated with Neonatal Septicaemia and Meningitis

1991 ◽  
Vol 65 (05) ◽  
pp. 483-486 ◽  
Author(s):  
Jaakko Parkkinen ◽  
Jörg Hacker ◽  
Timo K Korhonen
Keyword(s):  
Plasminogen Activator ◽  
Tissue Plasminogen Activator ◽  
Surface Protein ◽  
Protein S ◽  
Aminocaproic Acid ◽  
Bacterial Invasion ◽  
Dependent Manner ◽  
Plasminogen Activation ◽  
Plasmin Activity ◽  
Tissue Plasminogen

SummaryThe effect of Escherichia coli strains isolated from blood and cerebrospinal fluid of septic infants on plasminogen activation was studied. These strains typically carry a filamentous surface protein, S fimbria, that has formerly been shown to bind to endothelial cells and interact with plasminogen. The bacteria effectively promoted plasminogen activation by tissue plasminogen activator (t-PA) which was inhibited by s-aminocaproic acid. A recombinant strain expressing S fimbriae accelerated t-PA-catalyzed plasminogen activation to a similar extent as did the wild-type strains whereas the nonfimbriate recipient strain had no effect. After incubation with t-PA and plasminogen, the S-fimbriate strain displayed bacterium-bound plasmin activity whereas the nonfimbriate strain did not. Bacterium-associated plasmin generation was also observed with a strain expressing mutagenized S fimbriae that lack the cell-binding subunit SfaS but not with a strain lacking the major subunit SfaA. Both t-PA and plasminogen bound to purified S fimbriae in a lysine-dependent manner and purified S fimbriae accelerated t-PA-catalyzed plasminogen activation. The results indicate that E. coli S fimbriae form a complex with t-PA and plasminogen which enhances the rate of plasminogen activation and generates bacterium-bound plasmin. This may promote bacterial invasion and persistence in tissues and contribute to the systemic activation of fibrinolysis in septicaemia.

A Study of Proteolytic and Fibrinolytic Factors in the Human Prostate

1971 ◽  
Vol 25 (03) ◽  
pp. 481-498 ◽  
Author(s):  
Michelle Nijs ◽  
Christiane Brassinne ◽  
A Coune ◽  
H. J Tagnon
Keyword(s):  
Proteolytic Activity ◽  
Trypsin Inhibitor ◽  
Aminocaproic Acid ◽  
Soybean Trypsin Inhibitor ◽  
Clinical State ◽  
Plasminogen Activation ◽  
The Third ◽  
Human Plasminogen ◽  
Epsilon Aminocaproic Acid

SummaryAn analysis of the proteolytic factors contained in human prostatic tissue was performed in vitro. Casein, fibrinogen and fibrin, non-radioactive and radioiodinated were used as substrates.A first factor, called direct proteolytic activity, capable of proteolyzing casein without prior activation, is described. It had no effect on fibrinogen or fibrin, was inhibited by epsilon aminocaproic acid, but not by the soybean trypsin inhibitor. This shows that this proteolytic activity was quite different from plasmin.A second factor, called plasminogen proactivator, was demonstrated on bovine plasminogen in the presence of streptokinase, the latter being unable to produce direct activation of bovine plasminogen. Activation of this system resulted in the transformation of plasminogen into plasmin, capable of digesting casein as well as fibrinogen and fibrin. Epsilon aminocaproic acid and the soybean trypsin inhibitor inhibited this system. The properties of this proactivator show that it probably does not result from the presence of small amounts of plasminogen in the prostate. Urokinase, a factor present in human urine, is able to activate this proactivator under certain conditions.The third factor, called plasminogen activator, was capable of activating directly human plasminogen into plasmin. It was not active on bovine plasminogen. Epsilon aminocaproic acid and the soybean trypsin inhibitor were effective inhibitors. Addition of large volumes of human prostatic extract to human plasminogen resulted in a paradoxical decrease of the proteolytic activity suggesting the possible existence in the prostate of an inhibitor of this third factor.Possible relationships between these factors and the clinical state of fibrinolysis observed in some cases of disseminated prostatic cancer are discussed.

scholarly journals A cellular binding site for the Mr 55,000 form of the human plasminogen activator, urokinase.

1985 ◽  
Vol 100 (1) ◽  
pp. 86-92 ◽  
Author(s):  
J D Vassalli ◽  
D Baccino ◽  
D Belin
Keyword(s):  
Cell Migration ◽  
Plasminogen Activator ◽  
Plasminogen Activators ◽  
Plasminogen Activation ◽  
Blood Monocytes ◽  
High Affinity ◽  
Human Plasminogen ◽  
A Chain ◽  
Optimal Site ◽  
Extracellular Proteolysis

The secretion of plasminogen activators has been implicated in the controlled extracellular proteolysis that accompanies cell migration and tissue remodeling. We found that the human plasminogen activator urokinase (Uk) (Mr 55,000 form) binds rapidly, specifically, and with high affinity to fresh human blood monocytes and to cells of the monocyte line U937. Upon binding Mr 55,000 Uk was observed to confer high plasminogen activator activity to the cells. Binding of the enzyme did not require a functional catalytic site (located on the B chain of the protein) but did require the noncatalytic A chain of Mr 55,000 Uk, since Mr 33,000 Uk did not bind. These results demonstrate the presence of a membrane receptor for Uk on monocytes and show a hitherto unknown function for the A chain of Uk: binding of secreted enzyme to its receptor results in Uk acting as a membrane protease. This localizes plasminogen activation near the cell surface, an optimal site to facilitate cell migration.

Conformational Transitions in Escherichia coli Ribosomal RNAs as Visualized by Dedicated STEM

1988 ◽  
Vol 46 ◽  
pp. 176-177
Author(s):  
J.S. Wall ◽  
V. Maridiyan ◽  
S. Tumminia ◽  
J. Hairifeld ◽  
M. Boublik
Keyword(s):  
Ionic Strength ◽  
Three Dimensional ◽  
Conformational Transitions ◽  
Dark Field ◽  
Dimensional Structure ◽  
Ribosomal Rnas ◽  
Field Mode ◽  
Freeze Dried ◽  
High Resolution Images ◽  
Low Ionic Strength

The high contrast in the dark-field mode of dedicated STEM, specimen deposition by the wet film technique and low radiation dose (1 e/Å2) at -160°C make it possible to obtain high resolution images of unstained freeze-dried macromolecules with minimal structural distortion. Since the image intensity is directly related to the local projected mass of the specimen it became feasible to determine the molecular mass and mass distribution within individual macromolecules and from these data to calculate the linear density (M/L) and the radii of gyration.2 This parameter (RQ), reflecting the three-dimensional structure of the macromolecular particles in solution, has been applied to monitor the conformational transitions in E. coli 16S and 23S ribosomal RNAs in solutions of various ionic strength.In spite of the differences in mass (550 kD and 1050 kD, respectively), both 16S and 23S RNA appear equally sensitive to changes in buffer conditions. In deionized water or conditions of extremely low ionic strength both appear as filamentous structures (Fig. la and 2a, respectively) possessing a major backbone with protruding branches which are more frequent and more complex in 23S RNA (Fig. 2a).

Factors Involved In the Plasminogen Activation System in Human Breast Tumours

1994 ◽  
Vol 71 (05) ◽  
pp. 684-691 ◽  
Author(s):  
László Damjanovich ◽  
Csaba Turzó ◽  
Róza Ádány
Keyword(s):  
Epithelial Cells ◽  
Connective Tissue ◽  
Plasminogen Activators ◽  
Breast Tumour ◽  
Plasminogen Activation ◽  
Malignant Tumours ◽  
Plasminogen Activation System ◽  
Activation System ◽  
Malignant Breast ◽  
Pai 1

SummaryThe plasminogen activation system is a delicately balanced assembly of enzymes which seems to have primary influence on tumour progression. The conversion of plasminogen into serine protease plasmin with fibrinolytic activity depends on the actual balance between plasminogen activators (urokinase type; u-PA and tissue type; t-PA) and their inhibitors (type 1 and 2 plasminogen activator inhibitors; PAI-1 and PAI-2). The purpose of this study was to determine the exact histological localization of all the major factors involved in plasminogen activation, and activation inhibition (plasmin system) in benign and malignant breast tumour samples. Our results show that factors of the plasmin system are present both in benign and malignant tumours. Cancer cells strongly labelled for both u-PA and t-PA, but epithelial cells of fibroadenoma samples were also stained for plasminogen activators at least as intensively as tumour cells in cancerous tissues. In fibroadenomas, all the epithelial cells were labelled for PAM. Staining became sporadic in malignant tumours, cells located at the periphery of tumour cell clusters regularly did not show reaction for PAI-1. In the benign tumour samples the perialveolar connective tissue stroma contained a lot of PAI-1 positive cells, showing characteristics of fibroblasts; but their number was strongly decreased in the stroma of malignant tumours. These findings indicate that the higher level of u-PA antigen, detected in malignant breast tumour samples by biochemical techniques, does not necessarily indicate increased u-PA production by tumour cells but it might be owing to the increased number of cells producing u-PA as well. In malignant tumours PAI-1 seems to be decreased in the frontage of malignant cell invasion; i.e. malignant cells at the host/tumour interface do not express PAI-1 in morphologically detectable quantity and in the peritumoural connective tissue the number of fibroblasts containing PAI-1 is also decreased.

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