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:3.4.21.4 (trypsin)
42,187 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have investigated the interaction between concanavalin A-agarose (Con A-agarose) and thyroid peroxidase, an integral membrane protein found in the 105,000 X g, 1-h particulate fraction of thyroid tissue. An intact form of porcine thyroid peroxidase was obtained by solubilization with the nonionic detergent Triton X-100 and two fragmented, hydrophilic forms of the enzyme were prepared by trypsin treatment of the membrane. The three types of thyroid peroxidase bind to Con A-agarose and can be eluted with alpha-methyl-D-mannoside. The alpha-methyl-D-mannoside eluate of the most purified thyroid peroxidase preparation has been analyzed by polyacrylamide gel electrophoresis. Peroxidase activity corresponds with a glycoprotein band. The binding of thyroid peroxidase to Con A-agarose can be inhibited by sugars in the following order: alpha-methyl-D-mannoside greater than D-mannose greater than alpha-methyl-D-glucoside greater than D-glucose greater than D-galactose. This order of specificity is typical of Con A-sugar interactions. Furthermore, inactivation of the carbohydrate binding site of Con A by demetallization greatly reduces the extent of thyroid peroxidase binding. Reactivation of the carbohydrate binding site by the addition of Ca2+ and Mn2+ to demetallized Con A-agarose restores thyroid peroxidase binding. These and other experiments suggest that htyroid peroxidase is, like several other peroxidases, a glycoprotein. In addition, the interaction between thyroid peroxidase and Con A-agarose may provide a new purification tool for thyroid peroxidase.
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PMID:Interaction of thyroid peroxidase with concanavalin A covalently coupled to agarose. 1 48

We have demonstrated binding of purified pili from a strain of Escherichia coli to Vero cell monolayers as a model of prokaryotic-eukaryotic cell adherence. Pili bound to the tissue culture in a rapid reaction that did not require enzymatic activation. Attachment occurred optimally at pH 4-5 and could be inhibited by analogues of D-mannose, anti-pili antibodies, or by preincubation of tissue cells with mannose-specific plant lectins. Binding remained after treatment of the monolayer with glycosidases, trypsin, or a protease mixture but was enhanced after neuraminidase treatment. These results indicate that bacterial binding can occur via pili which act like lectins and presumably bind to mannose-containing glycoproteins on mammalian cell surfaces.
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PMID:Type I Escherichia coli pili: characterization of binding to monkey kidney cells. 2 33

Staphylococcus saprophyticus was found to differ from Staphylococcus epidermidis and Staphylococcus aureus by its ability to agglutinate sheep erythrocytes. On testing 30 strains of each species, 28 strains of S. saprophyticus and one strain each of the other two species, caused agglutination. Twenty-eight of 30 strains of staphylococcus cohnii and Staphylococcus xylosis failed to cause haemagglutination. The haemagglutinating activity of S. saprophyticus, when using a 10 per cent bacterial suspension was demonstrated in dilutions of 1:2-1:32. It was reduced twofold, at most, when exposing the bacteria to 56 degrees C for 30 minutes, while no agglutination could be demonstrated after treatment for 10 minutes at 86 degrees C. No haemagglutination could be demonstrated after treatment of the bacteria with 5 per cent solution of trypsin. Treatment of S. saprophyticus with 0.1 M EDTA did not affect the haemagglutinating activity, whereas exposure of the bacteria to 10 per cent trichloroacetic acid reduced the activity. The haemagglutination was D-mannose-resistant, and it was inhibited by homologous rabbit antiserum. The agglutinates dispersed when heated at 45-56 degrees C for 30 minutes. A few of the strains of S. saprophyticus tested also agglutinated human, bovine, and guinea pig erythrocytes.
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PMID:Haemagglutination by Staphylococcus saprophyticus and other staphylococcal species. 10 21

We have asked whether treatment of normal cultured cells with proteases, other hydrolytic enzymes, or serum can convert them into transient phenocopies of transformed cells with respect to the very high rate of hexose transport characteristic of transformed cells. Treatment of density-inhibited cultures of normal chick embryo fibroblasts with trypsin, plasmin, neuraminidase, or hyaluronidase stimulated their rate of 2-deoxyglucose uptake to a level only marginally higher than that seen in normal exponentially growing cultures, and only 35-45% of that seen in transformed cultures. Addition of the hydrolytic enzymes to growing cell cultures had little effect on 2-deoxyglucose uptake. Serum, however, could stimulate 2-deoxyglucose uptake all the way up to the transformed level. Even though the hydrolases and serum differed in their ability to stimulate 2-deoxyglucose uptake, both reagents were capable of stimulating cell division equally well. Evidence is presented suggesting that the hexose transport rate is controlled by serum factors, and that proteolysis can affect the response of the cells of these factors.
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PMID:Hydrolase and serum treatment of normal chick embryo cells: effects on hexose transport. 12 53

Dipolid human fibroblast-rich tissues contain a macromolecule with a molecular weight between 30,000 and 50,000 daltons which will inhibit the proliferation of fibroblasts in the G1 phase of the cell cycle (i.e., inhibit both 3H-thymidine uptake as well as the normal increase in cell number). The inhibitor is destroyed by trypsin but not by ribonuclease or deoxyribonuclease, and it is thermolabile. It has an acid IEP. It is not cytotoxic, and its inhibitory activity appears to be completely reversible. This fibroblast endogenous inhibitor does not interfere with the proliferation of DNA synthesis by human lymphocytes, bronchial carcinoma cells, or HeLa cells. The activity does not appear to be species specific. Therefore, we suggest that it is quite possible that the control of fibroblast proliferation resides in a fibroblast chalone. Diploid human fibroblasts, in contrast to chicken or mouse fibroblasts or heteroploid fibroblasts in general, stringently require serum for their proliferation. All of this mitogenic activity of calf serum can be concentrated in a molecular weight range around 100,000 daltons by ultrafiltration. All of the mitogenic activity within this molecular weight class can be concentrated at a pH of 5.2 via isoelectric focusing, and all of the activity at this isoelectric point can be concentrated in one peak on preparative polyacrylamide gel electrophoresis. This latter material is homogeneous at three different pH's in analytical gel electrophoresis as well as in SDS electrophoresis. This purified serum mitogen for diploid human fibroblasts in vitro also works in vivo and represents as much as 0.5% of calf serum protein, albeit there is much less of this protein in adult cow or horse. It is composed of two equal subunits weighing about 60,000 daltons each and contains about 2 moles of sialic acid, one S-S bond, and 6 moles of hexose per subunit. There is a reciprocal relationship between the biological activity of fibroblast inhibitor and serum mitogen, but there is no apparent direct interaction between these two proteins. Addition of pure serum mitogen to diploid human fibroblasts in vitro results in the release of commensurable chalone activity into the medium and a reciprocal loss of mitogen from the medium. Therefore, we propose that serum contains a single macromolecule which competes with endogenous chalone on the surface of diploid human fibroblasts and that this functions as an anti-chalone for the fibroblast.
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PMID:Circulating factors controlling cell proliferation. 13 64

We have examined the role of proteolytic activity in the genesis and maintenance of the transformed phenotype by growing cultures of chick embryo fibroblasts transfromed by Rous sarcoma virus either in medium containing plasminogen-free serum or in medium to which protease inhibitors were added. Alterations in morphology, adhesiveness, and hexose transport were used as markers for the transformed state. Addition of the trypsin inhibitors NPGB or Soy Bean Trypsin Inhibitor at concentrations which inhibited transformation-associated fibrinolysis restored adhesiveness and morphology to near normal, but did not affect the rate of hexose transport. Growth of Rous-infected cells in plasminogen-free medium blocked the appearance of morphological and adhesive alterations, but allowed the rate of hexose transport to increase to the transformed level. Thus we were able to separate the appearance of transformation-specific changes in morphology and adhesiveness (which apparently require fibrinolytic activity) from the increased rate of hexose transport (which is independent of fibrinolytic activity). Another trypsin inhibitor, TLCK, although it did not inhibit fibrinolysis, was very effective at restoring adhesiveness and morphology as well as hexose transport to normal. This raises the possibility that there is another, perhaps earlier, protease involved in the genesis of the transformed phenotype.
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PMID:Inhibition of protease activity in cultures of rous sarcoma virus-transformed cells: effect on the transformed phenotype. 16 81

The rate of hexose transport was compared in normal and virus-transformed cells on a monolayer and in suspension. It was shown that: 1) Both trypsin-removed cells and those suspended for an additional day in methyl cellulose had decreased rates of transport and lower available water space when compared with cells on a monolayer. Thus, cell shape affects the overall rate of hexose transport, especially at higher sugar concentrations. 2) Even in suspension, the initial transport rates remained higher in transformed cells with reference to normal cells. Scanning electron micrographs of normal and transformed chick cells revealed morphological differences only in the flat state. This indicates that the increased rate of hexose transport after transformation is not due to a difference in the shape of these cells on a monolayer.
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PMID:Cell shape and hexose transport in normal and virus-transformed cells in culture. 19 15

Two tumour-cell-aggregation factors, derived from rat ascites hepatoma cells, had different antigenicity; one was not absorbed by immunoadsorbent chromatography with anti-rat serum antibody and the other was. Their activities were both lost by digestion with trypsin, but remained unchanged by oxidation with periodate, suggesting the role of the protein portions in their molecules. The potency of the unabsorbed factor was inhibited specifically by alpha-methyl-D-mannoside or D-mannose, while that of the absorbed factor was inhibited specifically by N-acetyl-D-glucosamine, suggesting that these carbohydrates may be concerned with the respective receptor structures at the tumour-cell surface. The unabsorbed factor induced not only cell aggregation (as shown in the form of simple apposition) but also cell adhesiveness characterized by development of intermediate junctions, desmosomes and tight junctions, while the absorbed factor produced only simple apposition, suggesting their functional difference.
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PMID:Biochemical and morphological comparison of two tumour-cell-aggregation factors from rat ascites hepatoma cells. 20 72

The predominant surface glycopeptide from a clone of baby hamster kidney cells transformed by Rous sarcoma virus (C13/B4), metabolically labeled with L-[14C]fucose, has been characterized for the first time. This glycopeptide represents 19% of the total radioactivity removed by trypsin from the cell surface of the transformed fibroblasts and is more abundant in the transformed cells than in the normal counterpart. Purification of the glycopeptide after digestion with Pronase was by successive chromatography on DEAE-cellulose and Sephadex G-50. The monosaccharide content of the glycopeptide was 42, 127, 138, 114, and 243 nmol of fucose, sialic acid, galatose, mannose, and glucosamine, respectively. A partial structure of the glycopeptide was proposed from the results of sequential enzymatic degradation coupled with gas-liquid chromatographic analysis of the resultant monosaccharides. All of the enzymes used were purified and pretested on natural substrates and found to remove terminal monosaccharides of the correct configuration, quantitatively. The purification and properties of an alpha-L-fucosidase from rat testes were described. All of the radioactivity in the glycopeptide, recovered as fucose, was present at the core and was removed by treatment with this alpha-L-fucosidase. The proposed structure is a triantennary, completely sialylated, complex glycopeptide containing a core region of beta-D-mannose, beta-D-N-acetylglucosamine, and alpha-L-fucose.
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PMID:Partial structure of a membrane glycopeptide from virus-transformed hamster cells. 22 Oct 11

Incubation of fat cells with insulin increased glycogen synthase I activity without changing total synthase activity. This effect of insulin was dependent upon the particular lot of albumin present in the medium and was abolished by incubating cells with trypsin. Half-maximal activation of glycogen synthase was obtained with 8 microunits/ml of insulin, a concentration very similar to that which half-maximally stimulated 3-O-methylglucose uptake. The basal percentage of phosphorylase a activity was not detectably altered by insulin, although it was decreased by incubating cells with 5 mM glucose. Insulin (50 microunits/ml) markedly opposed actions of epinephrine (0.05 to 10 muM) to increase phosphorylase a activity and decrease glycogen synthase I activity, effects which were observed without glucose. Partial activation of glycogen synthase by insulin was seen after 1 min and complete activation after 4 min. Glucose alone produced a transient increase in synthase I activity. When cells were incubated with insulin plus glucose for 4 min, the increase in the percent synthase I activity was much greater than the additive effects of insulin and glucose alone. This potentiation of the effect of insulin on glucogen synthase I activity depended on the time of incubation with glucose and on the concentration of the hexose. If cells were incubated with cytochalasin B before insulin plus glucose, the effect of glucose was abolished. These results suggest that there are at least two mechanisms by which insulin can increase fat cell glycogen synthase I activity. One requires glucose and activation occurs secondary to an increase in glucose transport; where another mechanism(s) is operative even in the absence of glucose.
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PMID:Activation of rat adipocyte glycogen synthase by insulins. 40 14


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