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)

The mechanism by which macrophages recognize tumor cells is still unknown. We have studied interactions between rat liver macrophages and rat L 5222 leukemia cells. These tumor cells, but not normal leukocytes or erythrocytes, adhere to freshly isolated macrophages in vitro. Binding of tumor cells by macrophages can be inhibited by N-acetyl-D-galactosamine, D-galactose and more potently by glycoproteins with terminal N-acetyl-D-galactosamine or D-galactose residues. Tumor cell adhesion is calcium-dependent. The relevant leukemia cell membrane structures which bear terminal beta-D-galactosyl or related residues have been determined as trypsin- and pronase-sensitive, and hence may presumably be glycoproteins. The tumor cell receptor on liver macrophages appears to be a lectin with the carbohydrate specificity N-acetyl-D-galactosamine greater than D-galactose greater than L-fucose.
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PMID:Role of carbohydrates in rat leukemia cell-liver macrophage cell contacts. 624 36

Glycosaminoglycans synthesized in polymorphonuclear (PMN) leucocytes isolated from blood (peripheral PMN leucocytes) and in those induced intraperitoneally by the injection of caseinate (peritoneal PMN leucocytes) were compared. Both peripheral and peritoneal PMN leucocytes were incubated in medium containing [35S]sulphate and [3H]glucosamine. Each sample obtained after incubation was separated into cell, cell-surface and medium fractions by trypsin digestion and centrifugation. The glycosaminoglycans secreted from peripheral and peritoneal PMN leucocytes were decreased in size by alkali treatment, indicating that they existed in the form of proteoglycans. Descending paper chromatography of the unsaturated disaccharides obtained by the digestion of glycosaminoglycans with chondroitinase AC and chondroitinase ABC identified the labelled glycosaminoglycans of both the cell and the medium fractions in peripheral PMN leucocytes as 55-58% chondroitin 4-sulphate, 16-19% chondroitin 6-sulphate, 16-19% dermatan sulphate and 6-8% heparan sulphate. Oversulphated chondroitin sulphate and oversulphated dermatan sulphate were found only in the medium fraction. In peritoneal PMN leucocytes there is a difference in the composition of glycosaminoglycans between the cell and the medium fractions; the cell fraction was composed of 60% chondroitin 4-sulphate, 5.5% chondroitin 6-sulphate, 16.8% dermatan sulphate and 13.9% heparan sulphate, whereas the medium fraction consisted of 24.5% chondroitin 4-sulphate, 28.2% chondroitin 6-sulphate, 33.7% dermatan sulphate and 10% heparan sulphate. Oversulphated chondroitin sulphate and oversulphated dermatan sulphate were found in the cell, cell-surface and medium fractions. On the basis of enzymic assays with chondro-4-sulphatase and chondro-6-sulphatase, the positions of sulphation in the disulphated disaccharides were identified as 4- and 6-positions of N-acetylgalactosamine. Most of the 35S-labelled glycosaminoglycans synthesized in peripheral PMN leucocytes were retained within cells, whereas those in peritoneal PMN leucocytes were secreted into the culture medium. Moreover, the amount of glycosaminoglycans in peritoneal PMN leucocytes was significantly less than that in peripheral PMN leucocytes. Assay of lysosomal enzymes showed that these activities in peritoneal PMN leucocytes were 2-fold higher than those in peripheral PMN leucocytes.
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PMID:Comparative study on glycosaminoglycans synthesized in peripheral and peritoneal polymorphonuclear leucocytes from guinea pigs. 669 21

A further study has been made on the house dust mite extract, Dermatophagoides pteronyssinus, with emphasis on gel-filtrated fraction 2 (F2). The crude mite extract showed at least nine discs on polyacrylamide disc electrophoresis and contained less than 0.25% sialic acid and less than 0.5 mM hexosamine and no detectable uronic acid. From gel filtration of the crude extract a No 2 fraction (F2) with allergenic activity showed at least five components on SDS disc electrophoresis covering a molecular weight range of between 15,000 and 70,000. The major allergenic activity of F2 dissolved in pH 7-8 and 4-5 on an isoelectric focusing column. Affinity chromatography and lectins showed that allergenic activity did not relate to structures of N-acetyl-D-glucosamine or N-acetyl-D-galactosamine. Allergenic activity of the crude extract was no affected by peptic digestion and the mite digest prepared by trypsin and pronase showed a similar fractionation and activity profile as crude extract.
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PMID:Biochemical and allergenic properties of the house dust mite extract, Dermatophagoides pteronyssinus. 675 29

Plasmodium knowlesi merozoites were prepared by the polycarbonate sieving method of Dennis, Mitchell, Butcher & Cohen (1975). Merozoite function was assayed by their attachment to and invasion of rhesus erythrocytes at 37 degrees C. The early merozoites from the culture chamber were the most invasive, although maximum numbers of merozoites appeared later. Merozoites were most stable when incubated at room temperature (23 degrees C). At 37 and 0 degrees C invasiveness rapidly declined to zero. Attachment was rapidly lost at 37 degrees C but was retained at 0 degrees C. Attachment was unchanged in the pH range 6.8--7.9 but invasion was reduced at pH 7.9. The presence of L-fucose, D-galactose, D-glucose, D-mannose, N-acetyl-D-galactosamine or N-acetyl-D-glucosamine did not reduce invasion. Attachment and invasion were greatly reduced or abolished by the presence of 2.5 mM EDTA or EGTA, by lactoperoxidase-catalysed iodination of the merozoites, or by treatment of the merozoites with trypsin at a concentration of 1 micrograms/ml or greater for 10 min at 23 degrees C.
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PMID:Factors affecting the ability of isolated Plasmodium knowlesi merozoites to attach to and invade erythrocytes. 677 38

Human erythrocyte UDPgalactose : 2-acetamido-2-deoxy-alpha-D-galactopyranosylpeptide galactose beta(1 lead to 3) transferase (Galactosyltransferase) has been characterized in terms of detergent and metal ion requirements. Michaelis constants for donor and acceptor substrates, inhibition constant for N-acetylgalactosamine, pH optimum and ionic strength effects. The assay thus optimized permits initial velocity measurements. Galactosyltransferase was shown to be membrane-bound by demonstrating its association with erythrocyte ghosts after high and low ionic strength treatments to remove weakly-associated proteins. In the absence of detergents, no activity was detectable in sealed ghosts and inside-out vesicles derived from erythrocyte membranes. Enzyme activation by detergents paralleled solubilization of membrane proteins. Both latency and solubilization studies indicated a substrate inaccessible active site for the enzyme in situ in the membrane. Galactosyltransferase activity in resealed ghosts, leaky ghosts and inside-out vesicles was resistant to the action of trypsin, chymotrypsin or pronase applied as single agents. A mixture of these proteases, however, strongly reduced the enzyme activity in inside-out vesicles and leaky ghosts, indicating a cytosolic orientation for the active site of the galactosyltransferase.
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PMID:Human erythrocyte galactosyltransferase. Characterization, membrane association and sidedness of active site. 679 73

The cell body, neurite and growth cone of isolated retinal neurons have been compared on the basis of their ability to bind a number of fluorescently labelled lectins, each possessing a unique carbohydrate specificity. The susceptibility of the respective binding patterns following pretreatment of these fixed cells with either neuraminidase or trypsin was also investigated. Neuronal cell bodies displayed the most intense binding of each lectin, with localization of limulin binding (specific for sialic acid) predominantly to the neurite hillock, the point on the cell body from which the neurite projects. Limulin binding was almost totally abolished by pretreatment with either neuraminidase or trypsin. In contrast to the cell body, limulin binding to the neurite or growth cone was not detected. These regions of the cell apparently possessed sialic acid, however, since pretreatment with neuraminidase reduced wheat germ agglutinin binding (to N-acetylglucosamine) and markedly enhanced Dolichos biflorus agglutinin binding (to N-acetylgalactosamine) to both the neurite and growth cone. The initially low binding of Dolichos biflorus agglutinin to the neurite and growth cone was slightly enhanced by pretreatment with trypsin. Uniformly low levels of binding of either Ricinus communis agglutinin 60 (galactose, N-acetylgalactosamine) or R. communis agglutinin 120 (galactose) was observed over the entire neuron. R. communis agglutinin 120 binding was not enhanced by pretreatment with neuraminidase. Receptors for either concanavalin A (mannose, glucose) or Ulex europaeus agglutinin I (fucose) were abundant over the entire nerve cell with the former exhibiting more marked trypsin sensitivity. From these data, it is apparent that the repertoire of lectin binding sites of the neurite and growth cone of these differentiating nerve cells differs markedly from that of the cell body, which itself demonstrates some degree of regionalization.
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PMID:A cytochemical study of lectin receptors on isolated chick neural retina neurons in vitro. 689 37

The surfaces of uncapacitated, capacitated, and trypsinized guinea pig sperm have been compared using 10 lectins. A previously described assay was used to assess the degree and pattern of agglutination induced by each lectin. Our method of evaluating the agglutination pattern was significantly improved by observing assay plates with an inverted phase contrast microscope at 200 X 320 X magnification rather than with a dissecting microscope. Following in vitro capacitation or trypsinization, the agglutinability of sperm by SBA, DBA, and WGA increased, and the agglutination pattern induced by SBA, DBA, WGA, and RCA120 changed to a predominantly reticular form. These changes did not occur when sperm were incubated in Ham's F-10, a control medium which does not support capacitation. Since binding of these lectins is inhibited by N-acetyl-D-galactosamine (SBA, DBA), D-galactose (SBA, RCA120, DBA), or N-acetyl-D-glucosamine (WGA), we conclude that surface receptors containing these residues are affected by capacitation. By examining assay plates with an inverted phase contrast microscope, we were able to show that the change in the agglutination pattern for all four lectins was due to an increase in agglutinability of the principal piece of the flagellum. It is suggested that the modification of the principal piece detected by this lectin assay may be important in the development of activated motility. Results further show that capacitation and trypsin treatment affect the sperm surface in a similar manner, and are thus consistent with the idea that a trypsin-like enzyme may modify the sperm during capacitation.
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PMID:Detection of modifications in the tail of capacitated guinea pig sperm using lectins. 702 68

Milk fat globule membrane (MFGM) enclosing fat droplets in human milk was found to contain a high molecular weight glycoprotein which did not migrate in 10% acrylamide gel on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). This glycoprotein (termed PAS-0) was isolated by Sepharose CL-4B chromatography. Isolated PAS-0 gave one band on SDS-PAGE using 5% acrylamide gel (acrylamide : bisacrylamide = 4 : 1, w/w) and gave one peak on analytical ultracentrifugation, indicating its homogeneity. PAS-0 was rich in serine, threonine, proline, glycine, and alanine. In contrast, contents of sulfur-containing amino acids were very low. Fucose, galactose, N-acetylglucosamine, N-acetylgalactosamine, and sialic acid were detected as constituent sugars of PAS-0 and the total carbohydrate content was about 50%. Alkali-borohydride treatment suggested that the carbohydrate moiety was linked to the polypeptide core with O-glycosidic bond(s). There results suggested that PAS-0 was a mucin-like glycoprotein. PAS-0 was shown to be resistant to pepsin, trypsin and chymotrypsin digestion, but susceptible to Pronase and Subtilisin BPN'. Extraction of intact milk fat globules (cream) with MgCl2 and guanidine hydrochloride solutions suggested that PAS-0 was an intrinsic component of MFGM. Digestion of cream with Subtilisin BPN' demonstrated that PAS-0 was located on the external surface of fat globules and was accessible to molecules outside the globules. By agglutination-inhibition tests using eight lectins, PAS-0 was suggested to act as surface receptors for Ricinus communis agglutinin, wheat germ agglutinin and peanut agglutinin.
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PMID:Isolation and characterization of mucin-like glycoprotein in human milk fat globule membrane. 706 73

A major cell surface sialoglycoprotein with Concanavalin A receptor activity has been isolated from rat Zajdela ascites hepatoma cells. The sialic acid residues of the plasma membrane glycoproteins were specifically labeled by oxidation and NaIO4 followed by reduction with NaB3H4. Surface-labeled glycoproteins were released by short incubations with TPCK-trypsin at 37 degrees C and then separated by gel filtration on Sepharose 6B column. The predominantly labeled fraction, GP II2, was then purified by chromatography on DEAE-cellulose equilibrated with 0.05 M phosphate buffer, pH 7.5, and eluted with increasing molarities of NaCl. It was shown to be homogeneous by protein and carbohydrate staining on SDS-polyacrylamide gels, isoelectric focusing, rechromatography on DEAE-cellulose and immunoelectrophoresis. It has an apparent molecular weight of 110,000 daltons. The location of GP II2 on the cell surface was confirmed by the fact that it could be labeled metabolically with D-(3H) glucosamine and externally through the nonpenetrating periodate-NaB3H4 system. GP II2 could not be removed from the cell surface by high salt concentrations, chelator, or chaotropic agents but was released from the membrane by detergents. This suggests that GP II2 could be an integral protein. Analysis of the carbohydrate composition of GP II2 revealed galactose, N-acetylglucosamine, N-acetylgalactosamine, and sialic acid as major constituents and mannose as a minor one. This suggests that it contains carbohydrate chains both O- and N-linked to the polypeptide chain, most of them being O-linked. Finally, GP II2 has a potent Concanavalin A receptor activity. It inhibits the interaction between Concanavalin A and hepatoma cells and suppresses its effects on hepatoma cell proliferation.
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PMID:Purification and characterization of a major cell surface glycoprotein in Zajdela ascites hepatoma cells which displays a potent concanavalin A receptor activity. 706 81

Pure secretory immunoglobulin A was isolated from human milk by fractionation in gradients of pH and (NH4)2SO4 concentration followed by gel filtration. The hinge region containing all the O-glycosidically linked oligosaccharides was isolated en bloc after trypsin and pepsin hydrolysis and separated by gel filtration. The mixture of O-glycosidically linked oligosaccharides contained N-acetylneuraminic acid (NeuAc), fucose (Fuc), galactose (Gal), N-acetylglucosamine (GlcNAc) and N-acetylgalactosamine (GalNAc) in the molar ratio of 0.2:0.5:2.5:2:1 respectively. After beta-elimination several oligosaccharides were separated by a combination of ion-exchange chromatography and gel-filtration chromatography. The complete structure of four of these oligosaccharides was determined by methanolysis, methylation and mass spectrometry. The structure of the four oligosaccharides which are linked to serine or threonine residues of the hinge region are as follows: beta-Gal-(1 leads to 3)-GalNAc-ol; alpha-HeuAc-(2 leads to 3)-beta-Gal-(1 leads to 3)-GalNAc-ol; beta-Gal-(1 leads to 3)-[beta-GlcNAc-(1 leads to 6)]-GalNAc-ol; beta-Gal-(1 leads to 3)-[beta-Gal-(1 leads to 4)-beta-GlcNac-(1 leads to 6)]-Gal-NAc-ol. These oligosaccharides are more complex and heterogenous than the oligosaccharides linked to serine residues of the hinge region from myeloma serum immunoglobulin A1.
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PMID:Heterogeneity of the glycans O-glycosidically linked to the hinge region of secretory immunoglobulins from human milk. 721 51


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