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 characterized the binding of gamma-glutamyltransferase to three insolubilized lectins. Optimal binding was achieved in 2 hours at 25 degrees C for concanavalin A and at 4 derees C for ricinus communis agglutinin 120 and wheat germ agglutinin,and was also a function of the ratio of lectin protein to gamma-glutamyltransferase protein. The interaction of gamma-glutamyltransferase with these three lectins is specific, and release of bound enzyme by carbohydrates follows the same general order of specificity previously observed for the competition between mono or polysaccharides for the lectin carbohydrate binding sites. The binding of trypsin-solubilized liver gamma-glutamyltransferase to the three insolubilized lectins was virtually identical to that of detergent solubilized enzyme. We propose, therefore, that the release by proteolytic enzymes, of gamma-glutamyltransferase from plasma membrane matrix does not significantly alter its carbohydrate structure. We obtained great differences in binding to the three lectins between the liver, kidney, pancreatic and duodenal isoenzymes of gamma-glutamyltransferase. From this data we conclude that carbohydrate content and topography are important distinguishing features of gamma-glutamyltransferase isoenzymes.
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PMID:Interaction of gamma-glutamyltransferase from human tissues with insolubilized lectins. 4 83

Cross-reactive antigens of clover roots and Rhizobium trifolii were detected on their cell surfaces by tube agglutination, immunofluorescent, and radioimmunoassay techniques. Anti-clover root antiserum had a higher agglutinating titer with infective strains of R. trifolii than with noninfective strains. The root antiserum previously adsorbed with noninfective R. trifolii cells remained reactive only with infective cells, including infective revertants. When adsorbed with infective cells, the root antiserum was reactive with neither infective nor noninfective cells. Other Rhizobium species incapable of infecting clover did not demonstrate surface antigens cross-reactive with clover. Radioimmunoassay indicated twice as much antigenic cross-reactivity of clover roots and R. trifolii 403 (infective) than R. trifolii Bart A (noninfective). Immunofluorescence with anti-R. trifolii (infective) antiserum was detected on the exposed surface of the root epidermal cells and diminished at the root meristem. The immunofluorescent crossreaction on clover roots was totally removed by adsorption of anti-R. trifolii (infective) antiserum with encapsulated infective cells but not with noninfective cells. The cross-reactive capsular antigens from R. trifolii strains were extracted and purified. The ability of these antigens to induce clover root hair deformation was much greater when they were obtained from the infective than noninfective strains. The cross-reactive capsular antigen of R. trifolii 403 was characterized as a high-molecular-weight (greater than 4.6 times 10(6) daltons), beta-linked, acidic heteropolysaccharide containing 2-deoxyglucose, galactose, glucose, and glucuronic acid. A soluble, nondialyzable, substance (clover lectin) capable of binding to the cross-reactive antigen and agglutinating only infective cells of R. trifolii was extracted from white clover seeds. This lectin was sensitive to heat, Pronase, and trypsin. inhibition studies indicated that 2-deoxyglucose was the most probable haptenic determinant of the cross-reactive capsular antigen capable of binding to the root antiserum and the clover lectin. A model is proposed suggesting the preferential adsorption of infective versus noninfective cells of R. trifolii on the surface of clover roots by a cross-bridging of their common surface antigens with a multivalent clover lectin.
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PMID:Cross-reactive antigens and lectin as determinants of symbiotic specificity in the Rhizobium-clover association. 5

Preliminary characterization of two mouse thymus-dependent (T) lymphocyte xenoantigens, T25 and T200, which are selectively labelled by lactoperoxidase-catalysed iodination of T-cells, is described. Both molecules are membrane-bound glycoproteins. Fractionation of membrane vesicles prepared from BW5147 lymphoma cells by sedimentation through sucrose density gradients show that antigens T25 and T200 are in fractions enriched with plasma membrane. Moreover antigen T200 is partially degraded when viable cells are treated briefly with low concentrations of trypsin. Both molecules are efficiently solubilized in buffers containing sodium deoxycholate or Nonidet P-40, as measured by failure to sediment at 100000g for 60min. However, gel filtration on Sepharose 6B showed the presence of aggregated material in Nonidet P-40 extracts which was not found in deoxycholate-solubilized membranes. After solubilization in detergent, antigens T25 and T200 bind to, and may be specifically eluted from, columns of pea lectin--Sepharose or concanavalin A--Sepharose. Both molecules are heterogeneous when examined by polyacrylamide-gel electrophoresis in the presence of sodium dodecyl sulphate. As judged by its binding to columns of pea lectin, at least part of the heterogeneity of mouse thymocyte antigen T25 resides in its carbohydrate moiety.
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PMID:Preliminary characterization of two thymus-dependent xenoantigens from mouse lymphocytes. 6 76

Plasma membranes were isolated from the leukemia cell line ASL1w and extracted with detergent (DOC). DOC solubilized more TL activity than could be detected on isolated membranes. However, extraction of membranes with LDS or EDTA solubilized only 17% and 4%, respectively, of the activity. This indicated that TL was not loosely associated with the membrane but rather was integrated into the lipid bilayer. At low concentrations of DOC (0.05%), TL was found to be largely aggregated and was also prone to autolysis. Neither aggregation nor autolysis was observed at a higher DOC concentration (0.5%). The apparent molecular weight of TL in 0.5% DOC was determined by Sephadex G-200 chromatography to be about 65,000-70,000. Digestion of a 0.5% DOC extract of TL with either papain or trypsin produced a fragment of TL of about 35,000 molecular weight. These fragments were similar in size to a fragment produced by autolysis. These data suggested that a region of the TL molecule was very prone to proteolytic attack. The 35,000 molecular weight proteolytic fragments bound specifically to lentil lectin affinity columns, which indicated that they retained at least part of the carbohydrate present on the native molecule.
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PMID:Some structural properties of thymus leukemia antigen (TL) solubilized with detergent. 9 17

The effect of trypsin inhibitors (obtained from soybean, lima bean and ovomucoid) and Concanavalin A on fertilization in Bufo arenarum was tested. In order to study the effect of these substances at the level of the vitelline envelope of the oocytes, a new bioassay was designed. This bioassay employs coelomic oocytes to which some oviducal factors necessary for their fertility was added. Trypsin inhibitors block both the lytic effect of the acrosomal proteases on the vitelline envelope and fertilization. This indicates that the blockade of fertilization is a consequence of the inhibition of the lytic effect of the acrosomal proteases. Concanavalin A is effective as well in blocking the lytic effect of acrosomal proteases and fertilization. These effects are reversed by some sugar antagonists of the lectin, thus indicating that the effect of Concanavalin A is through its saccharide-binding capacity. These results suggested the involvement of glucosidic residues of the vitelline envelope in amphibian fertilization (the saccharide residues might be involved in the attack of the vitelline envelope by the acrosomal proteases). The possible mechanism of action of these substances is discussed.
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PMID:Effect of trypsin inhibitors and concanavalin A on the fertilization of Bufo arenarum coelomic oocytes. 9 6

Membrane glycoprotein biosynthesis of ascites hepatoma cells is followed by [14C]glucosamine and [3H]leucine incorporation into cells in culture. The rate of incorporation is strongly increased by the addition of Robinia lectin in culture medium. Labeled glycoproteins are released from lectin stimulated and non-stimulated cells by trypsin digestion. Studies of labeled trypsinates on sodium dodecyl sulfate gel electrophoresis and Sephadex G-200 filtration exhibit two fractions both labeled with [14C]glucosamine and [3H]leucine and having different molecular weights, one over 200000 and the other about 2000. Identical results are obtained when external membrane glycoproteins are solubilized by sodium deoxycholate. Comparison of surface glycoproteins isolated by trypsinization from control cells labeled with [3H]-glucosamine and from lectin stimulated cells labeled with [14C]glucosamine displays no significant qualitative differences between glycoprotein fractions released from both cell groups.
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PMID:Stimulation of the biosynthesis of membrane glycoproteins from Zajdela ascites hepatoma cells by Robinia lectin. 18 23

The observation of BOREK et al. (1973) on nonagglutinability of transformed rat liver cells by Lens culinaris lectin and our ultrastructural findings of a greater mobility of the Lens culinaris lectin receptors on transformed rat liver cells as compared to normal rat liver cells (ROTH 1975) initiated the present agglutination experiments on liver cells with lectins. For agglutination assay the microhemadsorption technique after FURMANSKI et al. (1973) was used with exception of several tests on EDTA-detached cells. The transformed rat liver cells exhibited, in contrast to the findings of BOREK et al. (1973), a positive microhemadsorption with Lens culinaris lectin as well as with Concanavalin A, Ricinus communis lectin and wheat germ agglutinin whereas the normal rat liver cells became positive only after a brief trypsin treatment. The significance of the difference in agglutinability of rat liver cells with Lens culinaris lectin and the other lectins used is discussed with regard to the cell-cell interaction mediated by lectins.
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PMID:Interaction of Lens culinaris lectin, concanavalin A, Ricinus communis agglutinin and wheat germ agglutinin with the cell surface of normal and transformed rat liver cells. 18 74

Exposure of normal lymphocytes to phytohaemagglutinin or other lectin mitogens results in increased concentrations of 5-phosphoribosyl-1-pyrophosphate (PP-ribose-P) within minutes. Subsequently, synthesis of purine nucleotides by both the de novo and the salvage pathways is facilitated. This change is prevented by proliferation-inhibiting concentrations of exogenous adenosine. The capacity of lymphocytes to metabolize both adenine and adenosine is increased several-fold by incubation with phytohaemagglutinin but the specific activities of the respective first-step enzymes are not significantly altered. These results suggest that the relatively low quantity of PP-ribose-P available in normal lymphocytes is a major factor limiting the synthesis of purine nucleotides and may be important for the maintenance of the quiescent state. Increased availability of PP-ribose-P may also be associated with proliferative activation of fibroblast-like cells: chick embryo fibroblast cultures released from density-dependent inhibition of growth by insulin, trypsin or serum rapidly increase the rate of adenine incorporation into nucleotides. Chick embryo fibroblasts transformed by Rous sarcoma virus, but not cells infected with the respective non-transforming leukosis virus, show PP-ribose-P concentrations higher than those observed in normal cells.
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PMID:Purine metabolism and control of cell proliferation. 20 61

Human cytomegalovirus (CMV) was inactivated by treatment with phytohemagglutinin (PHA) in contrast to herpes simplex virus (HSV), which was not. Approximately 90% of infectivity was lost following exposure of CMV to PHA. Greater reduction of infectivity, more than 99%, was obtained following pretreatment of cells with PHA than by direct mixture of the virus and the lectin. Protection of cells was still observed 48 hours after pretreatment of cells with PHA. No difference was found in sensitivity to PHA with 3 strains of CMV tested. PHA preparations from different sources were almost equally effective in inactivation of CMV, whereas leucoagglutinin had minimal effect. Our data suggest that the site of action of PHA occurs at the step(s) of penetration and/or uncoating. Resistance of CMV to trypsin was confirmed, and the enzyme had no effect on sensitivity to lectins.
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PMID:Inactivation of human cytomegalovirus by phytohemagglutinin. 20 93

Mammalian spermatozoa have been dissected by a variety of chemical techniques to yield free heads, tails with attached midpieces, and tails without mitochondria. By brief exposure to trypsin, mouse and rat spermatozoa were cleaved at the junction of the head and the tail, while human, guinea pig and rabbit spermatozoa were cleaved by trypsin only after prior incubation with a sulphhydryl reducing agent. Treatment with acid or base cleaved spermatozoa of all species examined. In contrast, exposure of spermatozoa to 1% sarkosyl NL-97 resulted in the quantitative cleavage of mouse cells without noticeable effect on the spermatozoa of the other species. Mitochondria were removed from the midpiece of intact sperm and isolated tails by gentle shaking after treatment with reducing agents. Homogeneous populations of spermatozoan subcellular components were obtained by density gradient centrifugation. Ultrastructural analysis showed that cleavage of mouse spermatozoa by trypsin occurs at a specific location in the neck of the cell without trypsin occurs at a specific location in the neck of the cell without observable damage to other cell structures. The basal plate remained attached to the head structures. In contrast cleavage of spermatozoa by sarkosyl or acid left the basal plate attached to the spermatozoan midpiece. Sarkosyl also removed the plasma membrane and extracted mitochondrial components. Treatment with acid or base also resulted in vesiculation of the plasma membrane and dissolution of the acrosome. Molecular probes have also been used to facilitate mapping of the cell surface. Each mouse spermatozoon has about 10-7 receptors for the lectin concanavalin A. Binding of fluorescein-labelled concanavalin A indicated that the majority of the receptors is in the acrosomal region; this polar distribution was confirmed by measurement of the number of sites on purified heads and tails. In addition, the low molecular weight probe ANS bound to the plasma membrane of spermatozoa from all species examined, with immediate immobilization of the cells. Ethidium bromide bound to the spermatozoan head without affecting motility.
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PMID:Chemical dissection of mammalian spermatozoa. 23 23


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