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)

The N and O substitution in wall peptidoglycan from Lactobacillus fermentum was studied in relation to growth phase, as well as the lytic activities and the effect of trypsin on them. The N-nonsubstituted sites were determined by dinitrophenylation techniques. The results indicate that an extensive substitution at the O groups takes place as cells go into the stationary growth phase, concomitant with a decrease in their lysozyme sensitivity. N-nonsubstituted residues, mainly glucosamine, occurred in both exponential-phase and stationary-phase walls but not in the corresponding peptidoglycans. Small amounts of N-nonsubstituted muramic acid were detected in walls and peptidoglycan from cells in the stationary growth phase only. N acetylation of isolated walls did not increase their lysozyme sensitivity but rather decreased it. Autolysis of walls was completely inhibited by the chemical modifications used. Trypsin stimulates the lysozyme sensitivity of native walls but has no effect on walls that had been O deacetylated and N acetylated. It is suggested that the effect of trypsin is due to its action as an esterase removing the O acetylation in lysozyme-resistant walls.
...
PMID:Lysis of modified walls from Lactobacillus fermentum. 117 37

1. The in vivo incorporation of radioactivity from [3H]glucosamine into a trypsin labile, cell surface sialoglycopeptide fraction (SGP) of Ehrlich ascites cells was studied in the presence and absence of puromycin pretreatment. The results indicated a much more complete inhibition of incorporation into the surface SGP than in the average intracellular acid insoluble glycoproteins. No evidence of turnover of the carbohydrate portion of the surface SGP independent of protein synthesis could be obtained. 2. However, when intact cells were incubated with labelled uridine 5'-diphosphate-N-actely glucosamine or cytidine 5'-monophosphate (CMP)-sialic acid there was some incorporation largely into acid insoluble material, suggesting the presence of glycosyl transferase activity in the surface. Further evidence for surface activity was obtained when neuraminidase pretreatment of intact cells stimulated incorporation of labelled CMP-sialic acid sixfold and almost all of the incorporated counts could be released by subsequent neuraminidase treatment. Furthermore, a much greater proportion of the incorporated counts could be released by papain than by trypsin treatment of the intact cells. These results suggest that the surface acceptor for exogenously added CMP-sialic acid is not identical to the endogenously synthesized trypsin labile surface SGP.
...
PMID:Cell surface sialoglycopeptide metabolism and surface glycosyl transferase activity in the Ehrlich ascites cell. 118 49

M. gallisepticum membranes were treated with 0.3M lithium diiodosalicylate (LIS) and, on average, 43% of the original membrane proteins were extracted. The extract contained particles with a sedimentation coefficient of 13S and some aggregated proteins. This LIS extract was immunogenic, stimulating the production of haemagglutination-inhibiting, growth-inhibiting and precipitating antibodies in rabbits. It was devoid of haemagglutinating (HA) activity for chicken erythrocytes but did inhibit the HA activity of membranes of M. gallisepticum. This inhibitory activity was destroyed by periodate and trypsin, but not by heat. By sedimentation equilibrium in a caesium chloride gradient, the LIS extract was separated into a lipoprotein-like and a glycoprotein fraction. The lipoprotein-like fraction contained the majority of the proteins present in the original extract, had HA activity and blocked antibody which inhibits haemagglutination. These activities were apparently due to the protein moiety, since they were not removed by extraction with n-butanol. The lipoprotein-like fraction behaved similarly to the unfractionated LIS extract in immunodiffusion tests and polyacrylamide gel electrophoresis, producing one periodic acid-Schiff positive band in the latter. The glycoprotein fraction consisted of about 66% carbohydrate and 33% protein. The sugar components were identified as glucose, galactose, glucosamine, galactosamine, glucuronic acid. The glycorprotein fraction did not possess HA but blocked the HA activity of M. gallisepticum membranes. In immunodiffusion it produced one faint precipitation band. The possible significance of glycoprotein in mycoplasma membranes has been discussed.
...
PMID:Dissociation of Mycoplasma gallisepticum membranes with lithium diiodosalicylate and isolation of glycoprotein. 121 14

The effects of serum and coatings of substrate-attached material (SAM, which remains tightly adherent to the substrate after EGTA-mediated removal of cells) on the kinetics of attachment of DNA-radiolabeled BALB/c 3T3. SV40-transformed 3T3, and concanavalin A-selected revertant cells to glass coverlips were studied. The presence of serum in the medium of attaching cells had a marked effect on (1) the initial time lag before stable attachment of cells, (2) the maximum level of attached cells, (3) the stability of attachment, and (4) pseudopodial spread of the cell over the substrate. These serum effects could be mimicked by measuring attachment in medium without serum and with use of serum-preadsorbed or 3T3 SAM-coated coverslips. Enzymatic treatment of serumpreadsorbed substrates indicated that the factor(s) in serum which affects attachment is very trypsin-sensitive. Serum preadsorption of substrates stimulated attachment of SVT2 cells in medium with serum in a manner very similar to the effects of 3T3 SAM coating, while attachment of 3T3 SAM coating, while attachment of 3T3 or revertant cells was unaffected. Slab gel electrophoretic analysis (PAGE-SDS gels) identified eight major serum proteins by Coomassie blue staining (a) which bind to the substrate in the absence of cells and (b) which persist on the substrate after growth to confluence of 3T3 or SVT2 cells; this suggests that major breakdown or serum-adsorbed components does not occur during growth of normal or transformed cells. Seven radioactive SAM proteins were detected by autoradiography in 3T3 or SVT2 SAM electropherograms -- two of which are high molecular weight components which correspond to the glucosamine-radiolabeled hyaluronate proteoglycans observed previously; the remaining five are newly-identified proteins in SAM (one of these proteins appears to be actin). 3T3 and SVT2 cells have unique proportions of these seven components. The data are consistent with the idea that normal or virus-transformed cells do not attach directly to the culture substrate, but to specific classes of substrate-adsorbed serum proteins via deposition of specific classes of cell surface proteins and polysaccharides.
...
PMID:Substrate-attached serum and cell proteins in adhesion of mouse fibroblasts. 126 8

The purity of horseradish peroxidase isoenzyme C was demonstrated using isoelectric focusing, polyacrylamide gel electrophoresis at two pH values and cellulose acetate electrophoresis at two pH values. The glycopeptides obtained upon trypsin digestion were isolated using the plant lectin, concanavalin A, and were resolved using paper electrophoresis. The carbohydrate content of the native peroxidase was 86% accounted for by the carbohydrate content of the glycopeptides thus suggesting little loss of carbohydrate during glycopeptide isolation and purification. In each of the seven glycopeptides isolated glucosamine was associated with asparagine, thus suggesting the carbohydrate chains are covalently bound to the peptide chain through N-glycosidic linkages. The purity of each glycopeptide was demonstrated by the sequential release of single amino acid residues by Edman degradation. As six glycopeptides had unique amino acid sequences, it was concluded that the carbohydrate prosthetic group was distributed in at least six units along the protein backbone. Five glycopeptides possessed the amino acid sequence about the point of carbohydrate attachment of Asn-X-(Ser, Thr) where X is any amino acid. The size of the carbohydrate units ranged from 1600 to 3000 daltons. The predominant carbohydrate residues in each glycopeptide were mannose and glucosamine with lesser and varying amounts of fucose, xylose, and arabinose. There was no apparent correlation of the carbohydrate composition with the amino acid sequence.
...
PMID:The isolation and characterization of the glycopeptides from horseradish peroxidase isoenzyme C. 126 13

The glycoprotein which accounts for approximately 50% of the protein and all of the nonlipid carbohydrate of the cell envelope of Halobacterium salinarium (Mescher, M. F., Strominger, J. L., and Watson S. W. (1974) J. Bacteriol. 120, 945-954) has been purified and partially characterized. The glycoprotein has an apparent molecular weight of 200,000, is extremely acidic, and has a carbohydrate content of approximately 10 to 12%. The carbohydrate included neutral hexoses, amino sugar, and uronic acid. Information regarding the number, composition, and mode of attachment of the carbohydrate chains was obtained by isolation and examination of the glycopeptides derived from degradation of cell envelope protein with trypsin and pronase. Trypsin digestion resulted in two glycopeptides. One of these was large (approximately 55,000 daltons) and had most of the neutral hexose linked to it. The carbohydrate moieties consisted of di- and trisaccharides of glucosylgalactose and (uronic acid, glucose)-galactose attached via O-glycosidic linkages between galactose and threonine. The other tryptic glycopeptide had a relatively large heterosaccharide attached to it via an alkaline-stable linkage. The heterosaccharide contained 1 glucose, 8 to 9 galactose, 1 mannose, and 10 to 11 glucosamine residues, and approximately 6 residues of an unidentified amino augar. The alkaline stability of the linkage and the amino acid composition of glycopeptides resulting from Pronase digestion of the tryptic glycopeptide showed that the heterosaccharide was attached to an asparagine residue, presumably via an N-glycosylamine bond to the amide group. The intact glycoprotein has a single N-linked heterosaccharide, 22 to 24 O-linked disaccharides, and 12 to 14 O-linked trisaccharides per molecule. N- and O-glycosidic linkages are the most common carbohydrate-protein linkages in mammalian glycoproteins but, to our knowledge, this is the first report of either type of linkage in a prokaryotic cell envelope protein.
...
PMID:Purification and characterization of a prokaryotic glycoprotein from the cell envelope of Halobacterium salinarium. 127 Apr 19

Liver microsomal subfractions and Golgi membranes free from adsorbed and secretory proteins have a characteristic sugar composition. The ratio of mannose to galactose is largest in rough microsomes, smaller in smooth I microsomes, still smaller in smooth II microsomes, and smallest in Golgi membranes. There is about twice as much glucosamine in Golgi membranes and 3 times as much in smooth II microsomes as in the other microsomal subfractions. Golgi membranes are rich in sialic acid in comparison to rough microsomes and it is present at even higher levels in the two smooth microsomal subfractions. Increasing concentrations of deoxycholate preferentially remove protein-bound mannose and glucosamine, while releasing significantly less galactose. About half of the microsomal mannose and galactose can be liberated from the surface of intact microsomal vesicles by treatment with trypsin. When trypsin is added to permeable vesicles where the inside surface can be also attacked, an additional 20% of the total mannose but no additional galactose is liberated.
...
PMID:Distribution of protein-bound sugar residues in microsomal subfractions and Golgi membranes. 127 91

We have tested the hypothesis that some phenotypic characteristics of the lymphocytes from mice with lymphoproliferative disease (lpr) could be explained by abnormal glycosylation of membrane proteins. Lymph node cells from normal C57 BL/6 and from C57 BL/lpr mice were labelled with tritiated sugars. Membrane proteins were released with trypsin, then with pronase. After complete pronase digestion, glycopeptides were first separated on Bio Gel P-6 and then on Con A-Sepharose. Fractions not binding to Con A (Con A negative) were also separated on Lens culinaris agglutinin-Sepharose. Marked differences between normal and lpr cells were noticed. First, there were more glucosamine-labelled peptides with very high molecular weight (eluting fast on Bio Gel P-6) on lpr cells than on normal lymphocytes. Second, the proportion of mannose-labelled peptides binding to Con A was smaller in the lpr cells. Third, among the Con A negative peptides, the proportion binding to Lens culinaris agglutinin was higher in lpr cells. Thus, lpr cells seem to carry more alpha 1-6 fucosylated chains and larger size carbohydrates. These alterations were also confirmed by gel electrophoresis of lectin-selected iodinated cell surface antigens and seem to be restricted to a very limited number of peptides. Thus, there may be primary changes in glycosylation in lpr cells. Alternatively, the glycosylation pattern of lpr cells may be characteristic for a subpopulation of T-lymphocytes that is expanded in this disease, or for a certain stage of activation. A large proportion of Con A-negative, Lens culinaris-positive peptides is a rather unusual feature in murine cells and requires further investigation.
...
PMID:Comparison of the N- and O-linked glycopeptides of lymph node cells from C57 BL/6 lpr/lpr and C57 BL/6 mice. 129 47

The binding of 125I-labeled thrombin to rat peritoneal macrophages isolated 20 h after the ip injection of thioglycollate broth or lipopolysaccharide decreased to 20% of the value found in resident macrophages due to a decrease in the number of receptors. The binding returned to normal values within a week after the injection. The decline parallelled more or less the Vmax for the 5'-nucleotidase activity. This decrease in the binding of thrombin could not be explained by an immigration of monocytes into the peritoneal cavity, since the binding of 125I-labeled alpha 2-macroglobulin-trypsin complex increased 4.5-fold in the same cell population due to an increase in the number of receptors, and blood monocytes do not bind alpha 2-macroglobulin-trypsin complex. The increase in the binding of alpha 2-macroglobulin-protease complex parallelled an increase in the incorporation of glucosamine, although the latter did not increase to the same extent. Engulfment of plasma membrane after phagocytosis did not result in a decreased binding of thrombin, but preincubation at 37 degrees C with concanavalin A caused a minor reduction in the binding. There was a positive correlation between the binding of alpha 2-macroglobulin-trypsin complex and the fraction of polymorphonuclear leukocytes in the peritoneal exudate and a negative correlation between the binding of thrombin and the fraction of polymorphonuclear leukocytes in the exudate, when the inflammation was induced by a milder stimulus, sterile NaCl, indicating a common signal for the polymorphonuclear leukocyte chemotaxis and the macrophage differentiation.
...
PMID:In vivo inflammatory stimulation induces a transient change in the binding of thrombin to rat peritoneal macrophages. 131 45

We have previously shown that inhibitors of N-glycan processing alter both the cell surface carbohydrates and the homing properties in lymphoid cells. We have now studied the effects of the ionophore monensin (MON) on these parameters. Arrest in the spleen of [111In]-labelled BL/VL3 murine T lymphoma cells, injected intravenously was clearly reduced if the cells had been cultured for 24 h in the presence of monensin (0.1-1.0 microgram ml-1). We have characterized glycopeptides from BL/VL3 murine T lymphoma cells. Following labelling with tritiated precursors (fucose, mannose, galactose, glucosamine), surface glycopeptides from BL/VL3 murine T lymphoma cells, were released by trypsin and separated by gel filtration on Bio-Gel P6 and by affinity chromatography on immobilized lectins. After treatment with MON, a class of high molecular mass glycopeptides was no longer found. There were less complex and more high mannose glycans, as a consequence of a reduction of terminal glycosylation (sialylation, fucosylation or incorporation of N-acetyl-glucosamine). Similar findings were obtained with immunoprecipitated Thy-1 antigen. However, as estimated by flow cytometry analysis, the cell surface expression of Thy-1 was not reduced in MON-treated cells. Taken together our results show that cell surface oligosaccharides are modified dramatically, but that at least, certain cell surface antigens are present in normal amounts. It is tempting to speculate that changes in glycosylation account for the abnormal homing properties of MON-treated cells.
...
PMID:The effects of monensin on blood-borne arrest and glycosylation of BL/VL3 lymphoma cells. 134 14


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

---