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

---

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

Agglutination studies with 6 plant lectins indicated that the unaltered surface coat of Trypanosoma equiperdum isolated from rat blood lacks the carbohydrate molecules preferentially bound by these proteins. However, trypsin, pronase, chymopapain, or papain treatments exposed the binding sites for Concanavalin A and the phytohemagglutinins M and P and trypsinized cells were attached to Concanavalin A immobilized on agarose beads. Lipolytic, amylytic, and other proteolytic enzymes or other agents did not reduce or induce lectin agglutination and wheat germ, Anti A, and Anti H lectins did not clump the trypanosomes under any of the conditions employed. Carbohydrate residues resembling D-mannose or n-acetyl-D-galactosamine are therefore within the surface coat of T. equiperdum or on the cell membrane underneath it. The results are contrasted with the lectin induced agglutination of other parasite species and mammalian cells.
...
PMID:Lectin binding by trypanosoma equiperdum. 84 43

Soluble extracts of embryonic chick pectoral muscle contain lectin activity. This activity is assayed by agglutination of trypsin-treated, glutaraldehyde-fixed rabbit erythrocytes, and is blocked by specific saccharides such as thiodigalactoside and lactose. Lectin activity of the muscle extracts increased at least 1 order of magnitude between 8 and 16 days of chick embryo development, as the pectoral muscle differentiated. Preliminary purification was achieved by affinity chromatography on Sepharose 4B deprivatized with either asialo-bovine glycoprotein, or p-aminophenyl beta-D-thiogalactopyranoside as the ligand.
...
PMID:Lectin activity in embryonic chick muscle: developmental regulation and preliminary purification. 92 47

Living Trypanosoma musculi bloodstream trypomastigotes were agglutinated specifically with concanavalin A (ConA), wheat germ agglutinin (WGA), soybean agglutinin (SBA), and fucose-binding protein (FBP). The agglutination with these lectins of living cells from which the coat was removed by trypsinization was the same as with intact trypanosomes. Glutaraldehyde or formalin fixation did not affect the results with regard to agglutination with WGA, SBA, and FBP, but lower agglutination with ConA was observed upon fixation. By using a dense iron-dextran marker many fewer ConA marker particles were localized at the fine structural level in the intact than in trypsin-treated trypanosomes. On the basis of the results obtained by agglutination and electron microscopy, it is likely that fixation cross-links intact surface-coat components associated with the ConA binding sites. It is evident from the studies in which lectins were employed that ligands containing alpha-D-mannose, N-acetylglucosamine, N-acetylgalactosamine, and alpha-L-fucose are randomly distributed in the outer surface of the pellicular and flagellar membranes of T. musculi trypomastigotes. Results obtained with alpha-amylase- and dextranase-treated trypanosomes suggested that lectin-binding sugar ligands in the cell surface were not directly associated with alpha-1,4 or repetitive alpha-1,6 glucan-bonded polysaccharide moieties. Similar conclusions can be drawn on the basis of neuraminidase treatment with regard to N-acetylated neuraminic acids. After thorough washing, intact, but not trypsin-treated trypomastigotes were agglutinated specifically with antisera against whole mouse serum and against mouse IgG. Evidently, adsorbed constituents of mouse serum are regular components of the T. musculi surface coat. After incubation in dilute whole mouse serum or in mouse IgG solutions, also the trypsinized cells were agglutinated by the 2 antisera. No such results were obtained with trypsinized cells incubated in serum-free buffers. It was concluded that mouse serum proteins were readily readsorbed on, and firmly bound to the trypsinized cells' surfaces. Specific agglutinations were obtained with trypsinized cells after incubation in dilute rat, rabbit, bovine, and human sera and in solutions of rat and rabbit IgG in reactions with the corresponding antisera. It seems, therefore, that the host serum proteins are adsorbed nonspecifically to the cell surface of trypsinized T. musculi bloodstream forms. When examined by electron microscopy, the intact trypomastigotes were covered by an ununiform, slightly granular, fibrillar extracellular coat, applied to the entire outer lamina of the pellicular and flagellar membranes. No indication of such a coat was noted in the trypsinized organisms. Flocculent surface coat-like matrix could, however, be discerned in cells which, after trypsinization, were incubated in various sera.
...
PMID:The cell surface of Trypanosoma musculi bloodstream forms. II. Lectin and immunologic studies. 93 83

We have investigated the receptor site activity present on 6C3HED tumor cells for concanavalin A, fava, lentil and pea lectins. The binding of the tritiated lectins to the tumor cells was inhibited by methyl-alpha-D-mannoside but not by D-galactose. The number of binding sites for the lectins was 3.5-10(6)/cell for concanavalin A, 3.3-10(6)/cell for fava, 3.6-10(6)/cell for lentil and 4.8-10(6)/cell for pea. The apparent association constants were 3.6 and 1.3 muM-1 for concanavalin A, 3.9 muM-1 for fava, 4.2 muM-1 for lentil and 4.6 and 0.6 muM-1 for pea. Competitive inhibition studies showed that lentil was a good inhibitor of pea binding; concanavalin A was a poor inhibitor of pea binding; and fava was a better inhibitor than concanavalin A but not as good as lentil. Reciprocal inhibition experiments indicated that concanavalin A and pea may bind to different receptors as well as to common receptors. This was also indicated by the observation that trypsin or protease treatment of the cells decreased the binding of pea lectin by 20-40 percent whereas concanavalin A binding was unaffected.
...
PMID:Studies on 6C3HED murine ascites tumor cell receptors for mannosyl-binding lectins. 95 11

Phytohemagglutinin M (PHAM) has been purified from the commercial mixture of proteins produced by Phaseolus vulgaris, using a Sepharose-thyroglobulin column. The protein gave one band on gel electrophoresis and two bands on SDS-gel electrophoresis (mol. wt. 33 700 and 32 100, respectively). Molecular weight determination by ultracentrifugation gave a value of 61 200 +/- 700. The protein had a minimum sugar content of 16%. Binding studies of PHAM to purified rat spleen lymphocytes have been performed at 0, 25, and 37 degrees C. It was shown that the cells bound about the same amount of lectin at 0 and 37 degrees C, but less protein was bound at 25 degrees C. The binding phenomenon showed saturability at all temperatures. Data were analyzed by Scatchard plots and two kinds of binding sites were found. High-affinity sites and low-affinity sites have been characterized in terms of association constants and (apparent) number. It was also shown that cells treated with trypsin or sodium azide bound less lectin. Bound concanavalin A did not appear to affect the amount of bound PHAM, but its influence was reflected in the value of the association constant for the binding of PHAM. Unlabelled PHAM was shown to displace radioactive PHAM from the cells, but could not remove bound concanavalin A. The significance of these results is discussed in terms of the fluid plasma membrane model and cellular metabolism.
...
PMID:The binding of phytohemagglutinin M to rat spleen lymphocytes. Quantitative studies. 95 51

Concanavalin A aggregated gel-filtered platelets in 0.9% NaCl solution signifying cross-bridging by the lectin. Aggregation of these platelets by concanavalin A was temperature dependent; it did not occur at 0-4 degrees C unless the platelets were previously trypsinized. The level of aggregation of trypsinized platelets by concanavalin A at 0-4 degrees C was similar to that of untreated platelets at 37 degrees C. It is suggested that trypsin facilitates platelet aggregation by concanavalin A at 0-4 degrees C by causing a configurational change in membrane glycoproteins which orientates concanavalin A receptor sites into positions that favour lectin cross-bridging. Concanavalin A failed to aggregate platelets in plasma. Radioisotope studies showed that the amount of [3H]concanavalin A which combined with platelets in plasma was extremely low compared with gel-filtered platelets in saline. The aggregation of Ehrlich ascites cells by concanavalin A was considerably reduced when platelet-free plasma was added to the medium suggesting that it was due to the presence of concanavalin A-reactive components in the plasma. Concanavalin A inhibited the ADP-induced aggregation of platelets suspended in plasma or in a salts solution supplemented with calcium and fibrinogen, although the inhibitory effect was more conspicuous in the latter case. The results suggests that concanavalin A produces its inhibitory effect on ADP-induced platelet aggregation by interacting with membrane glycoproteins, and this further suggests their involvement in aggregation.
...
PMID:On the susceptibility of human platelets to aggregation by concanavalin A and the effect of this lectin on their response to ADP. 97 36

1. Mitochondria were isolated from developing endosperm of Ricinus communis and were fractionated into outer membrane and inner membrane. The relative purity of the two membrane fractions was determined by marker enzymes. The fractions were also examined by negative-stain electron microscopy. 2. Membrane fractions were sequentially extracted in the following way. (a) Suspension in 0.5M-potassium phosphate, pH7.1; (b)suspension in 0.1M-EDTA (disodium salt)/0.05M-potassium phosphate, pH7.1; (c) sonication in 0.05M-potassium phosphate, pH7.1;(d)sonication in aq. Triton X-100 (0.1%). The membranes were pelleted by centrifugation at 100 000g for 15 min, between each step. Agglutination activity in the extracts was investigated by using trypsin-treated rabbit erythrocytes. 3. The addition of lactose to inner mitochondrial membrane resulted in the solubilization of part of the lectin activity, indicating that the protein was attached to the membrane via its carbohydrate-binding site. Pretreatment of the membranes with lactose before tha usual extraction procedure showed that lactose could extract lectins that normally required more harsh treatment of the membrane for solubilization. 4. Lectins extracted from inner membranes were purified by affinity chromatography on agarose gel. Polyacrylamide-gel electrophoresis of purified samples in sodium dodecyl sulphate indicated that at least part of the lectin present in inner mitochondrial membrane was identical with the R. communis agglutinin of mol.wt. 120 000.
...
PMID:Lectins as membrane components of mitochondria from Ricinus communis. 100 61

The interaction of concanavalin A (Con A) with isolated adipocytes was studied using Con A-Sepharose beads in the affinity binding buoyant density method previously used to study insulin receptors. Free Con A-Sepharose beads could be separated from the bound beads (cell-bead complexes) by sedimentation of the high density beads and floatation of the low density complexes. Sedimented and total beads could be determined by counting the radioactivity associated with [-125I]Con A coupled in tracer amounts to the beads. Various lines of evidence demonstrated the high specificity of binding. Soluble Con A, but neither insulin nor any of the other proteins tested, inhibited and reversed the binding of Con A-Sepharose to the cells. Whereas treatment of Con A- (and insulin-) derivatized beads with anti-insulin antiserum, and cells with trypsin, readily inhibited binding of insulin-Sepharose to cells, neither treatment inhibited Con A-Sepharose binding. According to the relative extents of inhibition and reversal of binding exhibited by 15 different carbohydrates, the saccharide binding sites on Con A-Sepharose appeared virtually identical with the known sites on free Con A. Protein-containing components of cell ghosts that were solubilized with Triton X-100 appeared to correspond to the Con A-Sepharose receptor sites on the basis of their ability to bind to Con A-Sepharose columns, be eluted with methyl alpha-D-mannopyranoside (MeMan) and be precipitated by the free lectin and redissolved by MeMan. According to (a) Normarski interference contrast microscopic examination of the topographical distribution of Con A-Sepharose beads and cells surrounding and bound to each other, and (b) absence of any apparent morphological changes in the cells due to binding, it is suggested that extensive clustering ("cap" or "macropatch" formation) of Con A receptors did not occur on the adipocyte as a consequence of the interaction of the cells with the Con A-Sepharose beads.
...
PMID:Interaction of carbohydrate binding sites on concanavalin A-agarose with receptors on adipocytes studied by buoyant density method. 113 60

The transplantabilities of trypsin and neuraminidase-treated 101-AA cells were compared with untreated cells. The cell doses required for growth were similar for enzyme-treated and control cells. Yet, trypsinized cells injected i.v. gave rise to less lung tumours and, in one experiment, they produced more extrapulmonary tumours than control cells or neuraminidase-treated cells. These findings were collated with some data on the effect of enzyme treatment on the tumour cell membranes, obtained by particle size analysis, cell electrophoresis, lectin agglutinability and sialic acid determinations. The importance of cell surface characteristics for specific metastasis patterns, in this case a peculiar "myotrophism", is discussed.
...
PMID:MCG101-AA, a new ascites tumour in C57 mice. 4. Influence of enzyme treatment on transplantability and some in vitro characteristics. 115 1

A reproducible quantitative assay for the lectin-mediated agglutination of human erythrocytes, depending on different rates of settling of agglutinated and nonagglutinated erythrocytes, was developed. This assay was used to study the aggregation of human erythrocytes by phytohemagglutinin-P. The aggregation of human erythrocytes by phytohemagglutinin-P was found to depend upon the metabolic state of the cells. Metabolically depleted erythrocytes agglutinated much less readily than did similar cells supplied with adenosine. This was not due to swelling and rigidity of the cells, since erythrocytes in hypotonic solution did not exhibit significantly altered phytohemagglutinin-P agglutination. Metabolically depleted erythrocytes, or erythrocytes from blood stored 8 weeks, lysed and resealed in the presence of ATP, were agglutinated by phytohemagglutinin-P to a much greater extent than control samples without ATP. The presence of Mg2+, either alone or with ATP, had little effect on the agglutinability of the resealed membranes. Low concentrations of Ca2+ (0.2 mM) had little effect on agglutinability, although high Ca2+ (5 mM) inhibited agglutinability of the resealed membranes somewhat. Both metabolically depleted erythrocytes and depleted erythrocytes, previously treated with adenosine, when treated with trypsin released similar amounts of sialic acid. The agglutinability of the trypsinized adenosine-supplemented cells increased more readily than did that of trypsinized metabolically depleted cells. The agglutination of erythrocytes was not affected by cytochalasin B (40 mug/ml). Vinblastine (0.2 mM) caused depleted erythrocytes to agglutinate similarly to adenosine-supplemented erythrocytes, but had no effect on the agglutination of adenosine-supplemented erythrocytes. It is concluded that ATP in the human erythrocyte probably participates in the modulation of phytohemagglutinin-P agglutinability. This is not a consequence of the more rigid membrane known to accompany ATP depletion in the erythrocyte, or of the effect of ATP levels on Ca2+ or Mg2+ content. It appears likely that ATP modulates human erythrocyte phytohemagglutinin-P agglutinability through interaction, direct or indirect, with a membrane-associated component, which might also be sensitivie to vinblastine.
...
PMID:Effect of metabolic state on phytohemagglutinin-P agglutination of normal human erythrocytes. 118 76


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>

---