Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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 biosynthesis of distinct prostatic and lysosomal acid phosphatases is demonstrated using a human prostatic carcinoma cell line, PC-3SF12. The biosynthesis and maturation of the acid phosphatases was studied by metabolic labeling with radioactive leucine, specific immunoprecipitation, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and fluorography. Of the tartrate-inhibitable acid phosphatase activity in PC-3SF12 cells, 60% is lysosomal and 10% is prostatic. The lysosomal-type acid phosphatase is synthesized as precursor with a molecular weight of 68,000, some of which is converted to higher-molecular-weight precursor polypeptides (Mr 71,000 and 77,000). The multiple forms of the precursors are due to differences in the carbohydrate chains on the enzyme because biosynthesis in the presence of tunicamycin eliminates the precursor multiplicity. The initial precursor (Mr 68,000) is processed to a mature polypeptide (Mr 49,000), via intermediates with molecular weights of 62,000 and 59,000. The mature polypeptide is degraded to smaller polypeptides with molecular weights of 30,000, 28,000, and 25,000. Precursor polypeptides of the lysosomal-type enzyme are secreted in the medium. Prostatic acid phosphatase is synthesized as a precursor with a molecular weight of 110,000, which is processed via several intermediates (Mr 99,000-93,000, 77,000, and 55,000) to a mature polypeptide with a molecular weight of 49,000. Particularly during cell homogenization, or lysis, the mature polypeptide is rapidly degraded to an immunoprecipitable polypeptide with a molecular weight of 20,000. None of these polypeptides is secreted in detectable amounts into the medium. Precursors and mature and smaller polypeptides are present in human prostate extract and seminal fluid. Proteolytic degradation of prostatic acid phosphatases in cells and tissues is probably catalyzed by a plasmin-like or related trypsin-like enzyme because degradation of the mature prostatic phosphatase polypeptide is completely prevented by addition of the plasmin inhibitor bovine pancreatic trypsin inhibitor. Prostatic- and lysosomal-type acid phosphatases are eventually stored at least in part in two different types of cell organelles. Testosterone does not influence the biosynthesis and secretion of either acid phosphatase in this cell line.
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PMID:Biosynthesis and processing of prostatic and lysosomal acid phosphatases in a prostate carcinoma cell line PC-3SF12. 294 40

Plasmin was recently reported to inhibit platelet aggregation. We report here on the interaction of plasmin with the adenylate cyclase system of human platelets. Human plasmin caused a dose- and time-dependent increase in adenylate cyclase activity when added to a crude platelet membrane preparation. Both basal and prostaglandin E1-stimulated adenylate cyclase activity doubled in presence of plasmin. This stimulatory activity was shared by papain and alpha-chymotrypsin, but not by thrombin which displayed a slightly inhibitory effect. Plasmin not only stimulated platelet adenylate cyclase activity, but also suppressed the GTP-dependent alpha 2-adrenergic inhibition, thereby producing a five- to six-fold increased activity measured in the presence of adrenaline and GTP. These effects of plasmin on the adenylate cyclase system were suppressed by the addition of the protease inhibitor leupeptin, and of soybean trypsin inhibitor, indicating that proteolysis mediated these effects. We also examined the adenylate cyclase activity in membranes prepared from intact platelets incubated with increasing doses of plasmin. Incubation of platelets with plasmin concentrations as low as 0.25 mg/ml resulted in an irreversible increase in membrane adenylate cyclase activity and suppression of the adrenaline-mediated inhibition of enzyme activity. These results suggest that the proteolytic stimulating effect of plasmin on the platelet adenylate cyclase system may account for the inhibition of platelet aggregation.
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PMID:Plasmin: a possible physiological modulator of the human platelet adenylate cyclase system. 295 Oct 52

A catalytically active, human microplasmin was produced by incubation of [Lys]plasmin in buffer at pH 11.0 for up to 12 hr. The microplasmin was purified by affinity chromatography that used lysine-Sepharose and soybean trypsin inhibitor-Sepharose columns. It is homogeneous and pure by electrophoretic analysis in NaDodSO4/polyacrylamide gels and by gel filtration on a Superose 12 column. The molecular weight of the microplasmin determined by NaDodSO4 gel electrophoresis is 29,000 and 26,500 under reducing condition, whereas the molecular weight of native plasmin is 76,500. Microplasmin consists mainly of the ligh (B) chain of native human plasmin and possesses one active site per protein molecule when titrated with p-nitrophenyl p'-guanidinobenzoate. Microplasmin hydrolyzes the peptide substrate NH2-D-Val-Leu-Lys-p-nitroanilide (S-2251) with a Km of 0.361 +/- 0.017 mM and a kcat of 40.3 +/- 3.3 s-1 at pH 7.4 and 37 degrees C, whereas native plasmin has a Km of 0.355 +/- 0.002 mM and a kcat of 27.9 +/- 0.3 s-1 under the same conditions.
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PMID:Preparation and purification of microplasmin. 296 Sep 74

Enzymatic formation of acid-stable trypsin-plasmin inhibitors (ASTPIs) in human plasma with several proteinases, particularly SH-proteinases, was demonstrated. The maximal activity obtained with bromelain was 40 U/ml plasma, which corresponded to about a 10-fold increase as compared to the untreated control plasma (4.2 U/ml). Gel filtration revealed at least two ASTPI activity peaks of molecular weight 16,000 (main peak) and 8000 (minor peak). The main ASTPI was further purified by trypsin-Sepharose affinity chromatography, isoelectric focusing and gel filtration on Sephadex G-75 superfine. The purified inhibitor was found to be identical to the active fragment of plasma ASTPI or urinary trypsin inhibitor (UTI) formed by bromelain treatment. It had an isoelectric point (pI) of 3.7, a molecular weight of 16,000 by SDS-polyacrylamide gel electrophoresis and was a glycine- and glutamic acid-rich protein lacking histidine. The NH2-terminal amino acid sequence was H2N-(Lys)-Glu-Asp-Ser-X-Gln-Leu-Gly-Tyr-Ser-Ala-Gly-Pro-X-Met-Gly-Met-Th r-X-Arg - Tyr-Phe-Tyr-... COOH, which was homologous to the Lys22-Met36 part (or Glu23-Met36 part; 30% of the total) of the plasma ASTPI or UTI molecule (molecular weight 70,000-80,000 by gel filtration). The purified ASTPI displayed the same antigenicity as UTI and exerted strong inhibitory effects on trypsin, chymotrypsin and plasmin amidolysis, but had a much lesser effect on plasmin fibrinolysis. It also strongly inhibited non-plasmic fibrinolysis with human leukocyte proteinase and earthworm proteinase.
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PMID:Acid-stable trypsin-plasmin inhibitors formed enzymatically from plasma precursor protein. 296 15

A functionally active human microplasminogen without kringle structures was produced by incubation of plasminogen with urokinase-free plasmin at an alkaline pH. The microplasminogen was purified by affinity chromatography on lysine- and soybean trypsin inhibitor-Sepharose and by chromofocusing. Human plasminogen is specifically cleaved at Arg529-Lys530 by plasmin to form microplasminogen, which consists of a single polypeptide of 261 residues from the COOH-terminal portion of native plasminogen. It has an Mr of 28,617, calculated from the sequence, which is consistent with the molecular weight determined by sodium dodecyl sulfate gel electrophoresis. Microplasminogen is a slightly basic protein and is eluted from a chromofocusing column at pH 8.3. It can be activated by urokinase and streptokinase to a catalytically active microplasmin. The specific amidolytic activity of microplasmin is about three times higher than Lys77-plasmin on a weight basis and is about the same on a molar basis. The activation of microplasminogen by streptokinase is slower than that of either Glu-plasminogen or Lys77-plasminogen. On the other hand, the activation of microplasminogen by urokinase is faster than that of either of the latter. The Arg560-Val561 bond is cleaved during activation of both microplasminogen and native plasminogen.
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PMID:Isolation and characterization of microplasminogen. A low molecular weight form of plasminogen. 297 17

The effect of various proteases (kallikrein, plasmin, and trypsin) on sperm phospholipase A2 activity (PA2: EC 3.1.1.4) has been studied. The addition of trypsin to spermatozoa, isolated and washed in the presence of the protease inhibitor benzamidine, increased PA2 activity optimally with trypsin concentrations of 1.0-1.5 units/assay. In kinetic studies, all of the above proteases stimulated the deacylation of phosphatidylcholine (PC); in fresh spermatozoa, trypsin showed a higher activation potential than kallikrein or plasmin. In the presence of benzamidine, the activity remained at basal levels. Endogenous protease activity due to acrosin (control) resulted in an increase in PC deacylation compared to the basal level. The maximum activation time of PA2 activity by proteases was 30 min. Natural protease inhibitors (soybean trypsin inhibitor and aprotinin) kept the PA2 activity at basal levels and a by-product of kallikrein, bradykinin, did not significantly affect the control level. Protein extracts of fresh spermatozoa exhibited the same pattern of PA2 activation upon the addition of proteases, thus indicating that the increase in PA2 activity was not merely due to the release of the enzyme from the acrosome. All of these findings suggest the presence of a precursor form of phospholipase A2 that can be activated by endogenous proteases (acrosin) as well by exogenous proteases present in seminal plasma and in follicular fluid (plasmin, kallikrein). Thus, this interrelationship of proteases and prophospholipase A2 could activate a dormant fusogenic system: the resulting effect would lead to membrane fusion by lysolipids, key components in the acrosome reaction.
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PMID:Activation of phospholipase A2 of human spermatozoa by proteases. 297 29

The chick chorioallantoic membrane model (CAM) has previously been used to demonstrate cell proliferation, characteristic of both angiogenesis and fibrogenesis, after exposure to fibrin degradation products. This model has now been adapted for quantitative in vivo assay of collagen polypeptide synthesis and prolyl hydroxylase activity. The CAM exhibits oscillations in the level of labelled collagen, a pattern attributable to rapid intracellular degradation and proline recycling following a brief labelling period. Both collagen synthesis and prolyl hydroxylase activity are stimulated by fibrin degradation products (less than 50 000 MW). Such stimulation occurs by 3 h and precedes the rise in general protein synthesis. Extracts of healing mouse skin wounds, rich in proteases, inhibited collagen synthesis, as did pure plasmin. Conversely, stimulation was achieved when proteolytic activity was neutralized by soybean trypsin inhibitor. These findings help to explain the observation that fibroblasts and endothelial cells proliferate and migrate centrally in an inflammatory lesion without depositing collagen, whilst in a milieu of high proteolytic activity. More peripherally, where proteases are inactivated by antiproteases in inflammatory exudate, such cell movement ceases and collagen deposition is observed.
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PMID:The control of fibrogenesis: stimulation and suppression of collagen synthesis in the chick chorioallantoic membrane with fibrin degradation products, wound extracts and proteases. 300 65

The nature of vascular permeability factor (VPF) activity derived from serum-free conditioned medium containing cultured human malignant glial tumors has been further investigated. A 1000-fold purification was accomplished by sequential heparin-Sepharose affinity chromatography and high-performance liquid chromatography gel filtration chromatography steps. Vascular permeability factor activity falls into a molecular weight range of 41,000 to 56,000 D. Activity is bound to hydroxylapatite, carboxymethyl-Sepharose, phenyl-Sepharose, and heparin-Sepharose, whereas little or no activity was bound to diethylaminoethyl-Sephacel. Vascular permeability factor activity is trypsin- and pepsin-sensitive but is unaffected by treatment with ribonuclease A. This suggests that VPF is a hydrophobic, positively charged (cationic) polypeptide with a potentially biologically significant affinity for heparin. As most proteins are negatively charged (anionic) and have no affinity for heparin, a significant advantage was gained by performing these purification steps. The activity of VPF is not inhibited by coinjection of conditioned medium with soybean trypsin inhibitor; or hexadimethrine (both known antagonists of tissue plasminogen activator, Hageman factor, and serum kallikrein); or aprotinin (an antagonist of both plasmin and tissue kallikrein); or phenylmethanesulfonyl fluoride (a serine esterase (elastase) inhibitor); or pepstatin-A (an acid protease inhibitor which inactivates vascular permeability-inducing leukokinins). These data, together with the fact that VPF is produced and released into serum-free media, provides substantial evidence against it being one of the more commonly known serum-derived permeability mediators. Treatment with dithiothreitol inhibited VPF activity, indicating the presence of at least one essential disulfide bond in this molecule. Inhibition by dexamethasone of VPF expression in cultured malignant glial cells appears to be selective. Dexamethasone-induced inhibition of VPF was dose-responsive and was not associated with a parallel inhibition of cellular protein synthesis as determined by tritiated leucine incorporation into trichloroacetic acid-precipitable material. Inclusion of dexamethasone in the culture medium was not associated with altered cell viability or cell number. A series of in vivo studies confirmed the inhibition of VPF activity in test animals pretreated with dexamethasone. This steroid-induced inhibition was partially reversed by treatment of test animals with actinomycin D prior to exposure to dexamethasone.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Further characterization of malignant glioma-derived vascular permeability factor. 313 21

We have compared the distribution of two of the major secreted proteins of the porcine uterus within the endometrium of ovariectomized pigs which had received hormone replacement therapy for 30 days. The proteins studied, plasmin/trypsin inhibitor (PI) and uteroferrin (Uf), an iron-containing acid phosphatase, were both secreted into the uterine lumen by ovariectomized gilts given progesterone (P4) or P4 and 17 beta-estradiol but not by animals given 17 beta-estradiol alone or corn oil. The two proteins were localized immunocytochemically within the endometrium using an immunoperoxidase procedure. The results confirmed that production of PI and Uf was P4-dependent and demonstrated that the primary site of synthesis of PI was the surface and upper glandular epithelium, while Uf synthesis was confined to the glandular epithelium. A similar localization of PI and of Uf was found in endometrial tissue from pigs at day 13 (late luteal phase) of the estrous cycle. These results suggest that the uterine epithelium of the pig is regionally differentiated with regard to the production of P4-induced proteins.
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PMID:Differential patterns of secretory protein localization within the pig uterine endometrium. 315 52

Trypsin inhibitory activity from the hemolymph of the tobacco hornworm (Manduca sexta) was purified by affinity chromatography on immobilized trypsin and resolved into two fractions with molecular weights of 14,000 (M. sexta hemolymph trypsin inhibitor (HLTI) A) and 8,000 (HLTI B) by molecular sieve chromatography on Sephadex G-75. Electrophoresis of these inhibitors under reducing conditions on polyacrylamide gels gave molecular weight estimates of 8,300 for HLTI A and 9,100 for HLTI B, suggesting that HLTI A is a dimer and HLTI B is a monomer. Isoelectrofocusing on polyacrylamide gels focused HLTI A as a single band with pI 5.7, whereas HLTI B was resolved into two components with pI values of 5.3 and 7.1. Both inhibitors were stable at 100 degrees C and pH 1.0 for at least 30 min. HLTIs A and B inhibited serine proteases such as trypsin, chymotrypsin, and plasmin, but did not inhibit elastase, papain, pepsin, subtilisin BPN', and thermolysin. In fact, subtilisin BPN' completely inactivated both inhibitors. Both inhibitors formed low-dissociation complexes with trypsin in a 1:1 molar ratio. The inhibition constant for trypsin inhibition by HLTI A was estimated to be 1.45 x 10(-8) M. The HLTI A-chymotrypsin complex did not inhibit trypsin; similarly, the HLTI A-trypsin complex did not inhibit chymotrypsin, indicating that HLTI A has a common binding site for both trypsin and chymotrypsin. The amino-terminal amino acid sequences of HLTIs A and B revealed that both these inhibitors are homologous to bovine pancreatic trypsin inhibitor (Kunitz).
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PMID:Purification and characterization of two trypsin inhibitors from the hemolymph of Manduca sexta larvae. 316 77


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