Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.21.4 (trypsin)
 42,187 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The membrane-association of early biosynthetic form of cathepsin D has been demonstrated in hepatoma cells, and this membrane-association is not mediated by mannose 6-phosphate residues, implying that a mannose 6-phosphate receptor-independent mechanism operates in the sorting of cathepsin D. In this paper, to demonstrate whether cathepsin D is associated with the lysosomal membranes, an in vitro binding experiment was carried out employing lysosomal cathepsin D or microsomal procathepsin D isolated from rat liver. Immunoblotting analysis revealed that an intermediate form of cathepsin D was associated with the lysosomal membranes; this lysosomal membrane-associated cathepsin D was released from the membranes by washing with Na2CO3 (pH 10.6) but not with solutions containing mannose 6-phosphate. This suggested that cathepsin D associates with the membranes by ionic-interaction, and that the membrane-associated cathepsin D resides as a peripheral membrane protein in the lysosomal membrane fraction. To confirm that the intermediate form of cathepsin D specifically interacts with the lysosomal integral membrane proteins, the lysosomal membrane fraction was treated with trypsin and the binding experiment was conducted. The result showed that the binding capacity of cathepsin D to the lysosomal membranes was apparently abolished and cathepsin D did not rebind to the membranes. These data suggest that the intermediate form of cathepsin D is preferentially recognized by the lysosomal membranous protein which complements the mannose 6-phosphate receptor-dependent intracellular sorting mechanism.
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PMID:Cathepsin D associates with lysosomal membranous protein. 859 33

The alternatively spliced type III connecting segment (IIICS) of fibronectin (Fn) contains an amino acid sequence, CS-1, which is recognized by the integrin receptor, alpha 4 beta 1. Plasma Fn inhibits alpha 4 beta 1-dependent binding of lymphocytes and monocytes to CS-1 containing Fn derivatives poorly, suggesting limited exposure of the CS-1 sequence in Fn. To test the availability of CS-1 in plasma Fn, an antibody was raised to the synthetic peptide CS-1. The CS-1 sequence was found to be minimally exposed in plasma Fn; and immobilization of Fn, a model of matrix deposition, caused only a modest increase in its exposure. Digestion of Fn with selected proteases, however, induced substantial expression of the CS-1 sequence. The acid protease cathepsin D generated fragments of 31-33.5 kDa from the COOH-terminal heparin-binding domain of Fn which possessed high immunoreactivity with anti-CS-1. Digestion of Fn with cathepsin B also resulted in the exposure of CS-1 sequence in a 140 kDa fragment. Although the digestion of Fn with neutral proteases (neutrophil elastase, cathepsin G, chymotrypsin, trypsin) generated fragments from the COOH-terminal heparin-binding domain of similar molecular weight as with cathepsin D, the exposure of CS-1 did not occur. Exposure of the CS-1 region by the cathepsins was supported by cell adhesion experiments; digestion of Fn with cathepsins D and B transformed inert plasma Fn to an effective inhibitor of adhesion of lymphoblastoid B and T cells (Ramos, Jurkat, Molt-4) to an immobilized CS-1 conjugate. These results suggest that exposure of the CS-1 sequence in plasma Fn by proteolysis with cathepsins D and B, enzymes implicated in several pathological processes, may serve a regulatory function in cell adhesion. The adhesive function of the CS-1 region in intact Fn appears to be suppressed by the native conformation of the molecule.
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PMID:Proteolysis regulates exposure of the IIICS-1 adhesive sequence in plasma fibronectin. 871 84

A rapid and simple method for analyzing cathepsin D in breast tissue based on capillary zone electrophoresis (CZE) is described. After incubating the tissue extracts with hemoglobin as a substrate, a specific peptide is cleaved and separated by CZE in less than 5 min. This peptide is not produced by the action of pepsin or trypsin. It is inhibited by the addition of pepstatin, a specific inhibitor for cathepsin D. Human hemoglobin acted as a better substrate than bovine hemoglobin. The test compared well to a radioimmunoassay. We have shown that peptides can be stacked by the use of acetonitrile. The method demonstrates the advantages of CZE for assay of proteolytic enzymes in general.
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PMID:Analysis of cathepsin D from breast tissues by capillary electrophoresis. 887 48

Cell surface molecules on adherent cells that bind 125I-labeled fibronectin or its 70-kDa N-terminal fragment were identified by cross-linking with factor XIIIa and by photoaffinity labeling. Such cross-linking caused the 70-kDa fragment to become associated irreversibly to cell layers and was greater in cells treated with lysophosphatidic acid, an enhancer of fibronectin assembly and strong modulator of cell shape. Cross-linking of the 70-kDa fragment with factor XIIIa was to molecules that migrated in discontinuous sodium dodecyl sulfate-polyacrylamide gels at the top of the 3.3% stacking gel and near the top of the separating gel. Estimated sizes of these large apparent molecular mass molecules (LAMMs) were >>3 MDa and approximately 3 MDa. The label in 70-kDa fragment conjugated with 125I-sulfosuccinimidyl 2-(p-azidosalicylamido)-1, 3'-dithiopropionate was associated with >>3-MDa LAMMs without reduction and with approximately 3-MDa LAMMs after reduction and transfer of the cleavable label. The LAMMs were expressed on monolayer cells shortly after adherence, required both 1% Triton X-100 and 2 M urea for efficient extraction, and were susceptible to digestion with trypsin but not to cathepsin D digestion. Complexes of 125I-70-kDa fragment and LAMMs were also susceptible to limited acid digestion and Glu-C protease digestion but were not cleaved by chondroitin lyase or heparitinase. Neither the uncleaved complexes nor the cleavage products were immunoprecipitated with anti-fibronectin antibodies directed toward epitopes outside the 70-kDa region. Thus, cell surface molecules that are either very large or not dissociated in sodium dodecyl sulfate comprise the labile matrix assembly sites for fibronectin.
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PMID:Cross-linking of the NH2-terminal region of fibronectin to molecules of large apparent molecular mass. Characterization of fibronectin assembly sites induced by the treatment of fibroblasts with lysophosphatidic acid. 896 87

We studied the activity of lysosomal cathepsins B and D, neutral trypsin-like proteinase, and the content of trypsin inhibitors in the mammary glands of virgin, pregnant, and lactating rabbit females, as well as during the involution caused by lactostasis. The maximal activity of cathepsin D was found to occur in mammary glands under the condition of lactostasis. The activity of cathepsin B was practically identical in the mammary glands of virgin and pregnant animals and diminished during lactation. The activity of trypsin-like proteinase is low in the mammary glands of virgin animals, increases drastically during pregnancy, and diminishes during lactation. The content of trypsin inhibitors is maintained at a similar level in the mammary glands of virgin and pregnant animals and increases significantly during lactation. The caseinolytic activity of neutral proteinases has not been detected in the mammary glands of virgin rabbit females. At the lactation and involution stages, it is considerably lower than the activity of acidic proteinases and is possibly controlled by endogenous inhibitors.
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PMID:[The proteinase activity and content of trypsin inhibitors in the mammae of female rabbits in physiological states]. 899 89

N-Pepstatinyl-N'-dansyldiaminopropane (dansyl-pepstatin) was prepared by the coupling of pepstatin A and N-dansyl-diaminopropane. The dansyl-pepstatin obtained strongly inhibited pepsin activity by forming a 1:1 complex. The fluorescence of the dansyl group (excitation at 320 nm, and emission near 520 nm) increased with the formation of the complex. The increase in fluorescence of dansyl-pepstatin solution was proportional to the amount of added pepsin, chymosin and cathepsin D until dansyl-pepstatin was saturated by these enzymes and at higher protease concentrations the fluorescence did not increase further. Therefore, the net amounts of active pepstatin-sensitive carboxyl proteases could be determined by detecting the inflection point of increased fluorescence upon addition of the protease to a dansyl-pepstatin solution of known concentration. Moreover, the protease concentrations of many samples were obtained easily by measurements of increased fluorescence compared with that caused by authentic protease solution. The minimum detectable amount of pepsin was about 20 pmol. On the other hand, the fluorescence did not increase upon mixing with inactivated pepsin, chymotrypsin, or trypsin. The K(i) value of dansyl-pepstatin for pepsin was similar to that of pepstatin A. It was possible to determine the amount of chymosin contained in rennet by this method. The inactivation curve of pepsin in pH 6.5 buffer was also determined quickly and easily by the use of this method. This assay method for pepstatin-sensitive carboxyl proteases is very simple and easy, and it is possible to determine the net amounts of active pepstatin-sensitive carboxyl proteases even in crude mixtures.
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PMID:Determination of pepstatin-sensitive carboxyl proteases by using pepstatinyldansyldiaminopropane (dansyl-pepstatin) as an active site titrant. 937 5

Three protein inhibitors of proteolytic enzymes with molecular weights 21, 22, and 23 kD were isolated from potato tubers (Solanum tuberosum L.) by ammonium sulfate precipitation followed by gel and ion-exchange chromatography. The 21- and 22-kD proteins were shown to be serine proteinase inhibitors with different specificities. The 21-kD protein inhibits human leucocyte elastase and trypsin effectively, but it is less effective towards chymotrypsin. The 22-kD protein is an inhibitor of cysteine proteinases and suppresses the activities of papain, ficin, and bromelain with the same affinities. None of the isolated proteins inhibit subtilisin, pepsin, or cathepsin D. The 21-kD protein consists of two disulfide-linked polypeptide chains with molecular weights of 16.5 +/- 1 kD and 4.5 +/- 1 kD. The 22-kD and 23-kD proteins have a single polypeptide chain. The N-terminal 22-25 amino acid sequences of these three proteins were determined. These sequences have significant homology to other plant inhibitors from the Kunitz soybean inhibitor superfamily.
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PMID:Potato tuber protein proteinase inhibitors belonging to the Kunitz soybean inhibitor family. 948 70

The levels of marker enzymes for liver function, namely transaminases (SGPT, SGOT), creatine phosphokinase (CPK), alkaline phosphatase (ALP) and lactate dehydrogenase (LDH) were estimated in the sera of burn patients by administering trypsin: chymotrypsin preparation and comparing with an untreated group. Neutrophil proteolytic activity was also measured by assaying the lysosomal enzymes, namely neutrophil elastase and cathepsin D. Our earlier studies have already proved the efficacy of the above enzyme preparation to burn patients on the enhancement of vascular responses during the acute phase of the burn injury. These beneficial responses were brought about by the modulation of acute phase proteins expressed in the liver. Hence, it is of interest to study the changes in the above mentioned liver enzymes and certain lysosomal enzymes in the serum during the first 10 days of burn injury. The levels of liver and lysosomal enzymes markedly decreased in the treated group when compared with the untreated group. The enzyme studies clearly indicated that the initial rise in the liver enzymes was minimized in the treated group when compared with the untreated group and this helped in reducing the stress to the liver in the treated cases. The increase in the activity of alpha 1-antitrypsin and alpha 2-macroglobulin and decreased levels of C-reactive protein are attributed to the reduction of proteolytic enzyme levels in the treated group and minimizing the degradative changes during wound repair.
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PMID:Serum enzymatic changes modulated using trypsin: chymotrypsin preparation during burn wounds in humans. 956 24

Some proteolytic enzymes, trypsin, cathepsin B, cathepsin D, collagenase, elastase and their inhibitors, API and AMG, in serum of patients with colorectal carcinoma have been evaluated. Twenty patients belonged to stage B of colorectal carcinoma, twenty two patients to stage D (Astler and Coller classification) and a control group of thirty healthy volunteers were evaluated. Except in cathepsin D, patients exhibit higher enzymatic activities than healthy subjects, and both groups have all the proteolytic activities assayed in serum. Patients with disseminated disease have increased cathepsin B and collagenase levels, with a decrease of trypsin activity, showing an increment in API and AMG in sera. However, only the API values were significantly higher in patients with metastases. The coexistence of proteolytic activities in human sera together with their inhibitors is considered as well as the origin of these, tumoral and/or reactive, increments. Cathepsin B levels are raised in colorectal neoplasms and contribute to the destruction of the extracellular matrix and the proliferation of tumoral cells. There is evidence that a relation between collagenase like activity and tumor invasiveness exists. Cathepsin B and collagenase increases agree with the tumoral mass. On the other hand, trypsin decrease in metastatic carcinoma is probably related to the increment of their inhibitors, API and AMG, acute phase reactant proteins.
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PMID:Serum proteolytic activities and antiproteases in human colorectal carcinoma. 973 3

Many cancer patients develop tumor-reactive immune responses against antigens that are either expressed on the surface of tumor cells or released from them into the peripheral circulation. In this study, tumor-reactive immunoglobulins, present in the sera of ovarian cancer patients, were used to identify commonly recognized tumor-associated antigens on ovarian tumor cells. Western immunoblot analysis of cellular proteins, obtained from UL-1 ovarian tumor cell line, demonstrated several commonly recognized immunoreactive proteins. Two of these proteins (Mr 32,000 and 71,000) were selected for further investigation. Cellular proteins isolated from normal human ovarian epithelia, in a similar fashion, failed to exhibit corresponding immunoreactivity to these proteins. As an additional control, sera from normal (nontumor-bearing) individuals failed to identify these proteins on Western immunoblots. Furthermore, the absorption of the ovarian cancer patients' sera with normal ovarian epithelial tissue did not remove the reactivity of these two proteins. The Mr 32,000 and 71,000 proteins were subsequently purified by reverse-phase high-performance liquid chromatography, separated by SDS-PAGE, transferred to the polyvinylidene difluoride membrane, and digested with trypsin. These resulting tryptic fragments were separated by microbore reverse-phase high-performance liquid chromatography, and selected fragments were sequenced by mass spectrometry. This sequence analysis identified the Mr 32,000 protein as cathepsin D and the Mr 71,000 as glucose-regulated protein 78 (member of the heat shock protein family). The identities of cathepsin D and glucose-regulated protein 78 were confirmed by Western blot analysis. Additionally, the presence of cathepsin D was demonstrated in association with immune complexes in vivo. Currently, the common antigenic epitopes of these proteins are being defined.
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PMID:Humoral immune responses to cathepsin D and glucose-regulated protein 78 in ovarian cancer patients. 981 43


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