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)

Monolayers of human peripheral blood monocytes in the absence of exogenous proteins ingest a variety of natural particulate activators of the human alternative complement pathway. Sheep erythrocytes, which do not ordinarily activate the human alternative complement pathway or initiate a direct monocyte phagocytic response, can be modified to exhibit both functions by the deletion or alteration of membrane sialic acid residues. Enzymatic removal of the sialic acid residues with sialidase or their conversion to heptulosonic acid derivatives by limited oxidation with NaIO4 and reduction with BH4- have equivalent dose-response effects on the capacity of the altered sheep erythrocytes to initiate the phagocytic response by human monocytes or to activate the alternative pathway in human serum. The deposition of C3b on native sheep erythrocytes had little effect on their ingestion by human monocytes, whereas the fixation of C3b on desialated sheep erythrocytes had a synergistic effect on the percentage of monocytes ingesting such a particle. The monocyte receptor essential for ingestion of desialated sheep erythrocytes or desialated sheep erythrocytes bearing C3b was inactivated by concentrations of trypsin that also prevented the monocytes from ingesting natural activators of the human alternative complement pathway, but did not alter the receptors for C3b or the Fc portion of IgG. The capacity of the nonimmune host to respond to desialated particles by initiating the monocyte ingestive process and by activating the alternative complement pathway to provide the synergy afforded by C3b deposition on that particle represents a primitive biochemical basis for differentiation of nonself from self.
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PMID:Membrane sialic acid on target particles modulates their phagocytosis by a trypsin-sensitive mechanism on human monocytes. 27 97

Preparations of ECF-A derived from anaphylactic guinea-pig lung diffusates were subjected to a variety of enzymatic degradations. The enzymes employed had specificityonly for their appropiate subtstates. No effect was found following treatmentwith relatively high doses of trypsin, alpha-chymotrypsin, pronase, alkaline phosphataseand sialidase. In contrast a loss of activity was demonstated in a dose-dependent fashion following incubation with tyrosinase, aryl sulphatase and leucine aminopeptidase, suggesting that ECF-A contains a phenolic hydroxyl group, a sulphate ester anda peptide linkage with a free alpha-amino group.
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PMID:The effect of enzyme digestions on the activity of eosinophil chemotactic factor of anaphylaxis (EFC-A). 80 20

L-Selectin is a lectin-like receptor on lymphocytes which mediates their attachment to high endothelial venules (HEV) within lymph nodes. Previous work has identified HEV-associated endothelial ligands for L-selectin as sialylated, fucosylated and sulphated glycoproteins of approximately 50 kDa and approximately 90 kDa (Sgp50 and Sgp90). The interaction of L-selectin with these ligands is carbohydrate directed, reflecting the involvement of its amino-terminal, calcium-type lectin domain. It has been reported, and we have confirmed, that anti-Ly22 blocks the adhesive function of L-selectin without reducing its binding to a carbohydrate- based ligand PPME (phosphomannan monoester core from Hansenula hostii). The epitope for this monoclonal antibody depends on the epidermal growth factor (EGF) domain of L-selectin. We demonstrate that anti-Ly22 inhibits the interaction of L-selectin with both of the Sgps, thus establishing that the interaction of L-selectin with HEV can be accounted for by the Sgps. Furthermore, the interaction of trypsin fragments of Sgp50 with L-selectin is inhibitable both by an antibody that maps to the lectin domain and by anti-Ly22. These findings raise the possibility that anti-Ly22 is affecting the function of the lectin domain of L-selectin rather than directly antagonizing the EGF domain. Toward a further characterization of L-selectin's carbohydrate specificity, we show that Sgp50 is partially inactivated by the linkage-specific Newcastle Disease virus sialidase (alpha 2,3 linkage). We additionally demonstrate that a sialyl Lewis x-related tetrasaccharide can interact with L-selectin, as has also been demonstrated for E-selectin and P-selectin.
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PMID:Further characterization of the interaction between L-selectin and its endothelial ligands. 138 20

Streptococcus suis is a common cause of sepsis, meningitis, and other serious infections in young piglets and also causes meningitis in humans. The cell-binding specificity of sialic acid-recognizing strains of Streptococcus suis was investigated. Treatment of human erythrocytes with sialidase or mild periodate abolished hemagglutination. Hemagglutination inhibition experiments with sialyl oligosaccharides indicated that the adhesin preferred the sequence NeuNAc alpha 2-3Gal beta 1-4Glc(NAc). Resialylation of desialylated erythrocytes with Gal beta 1-3(4)GlcNAc alpha 2-3-sialyltransferase induced a strong hemagglutination, whereas no or only weak hemagglutination was obtained with cells resialylated with two other sialyltransferases. Binding of radiolabeled bacteria to blots of erythrocyte membrane proteins revealed binding to the poly-N-acetyllactosamine-containing components Band 3, Band 4.5, and polyglycosyl ceramides and to glycophorin A. The involvement of glycophorin A as a major ligand was excluded by the strong hemagglutination of trypsin-treated erythrocytes and En(a-) erythrocytes defective in glycophorin A. Sensitivity of the hemagglutination toward endo-beta-galactosidase treatment of erythrocytes and inhibition by purified poly-N-acetyllactosaminyl glycopeptides indicated that the adhesin bound to glycans containing the following structure: NeuNAc alpha 2-3Gal beta 1-4GlcNAc beta 1-3Gal beta 1-.
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PMID:Identification of N-acetylneuraminyl alpha 2-->3 poly-N-acetyllactosamine glycans as the receptors of sialic acid-binding Streptococcus suis strains. 140 Apr 20

The preparation of greater than 30 different hybridomas, all secreting IgM class antibodies against epiglycanin, a glycoprotein at the surface of the mouse mammary carcinoma cell line TA3-Ha, is described. The specificities of 10 of the antibodies, with affinity constants in the range of 10(8)-10(10) l/mol were compared in an enzyme competitive binding assay. The affinity of epiglycanin was strongly reduced for all antibodies tested by incubation with periodate (10 mM, 4 degrees C) and was reduced for most of the antibodies by endo-alpha-N-acetyl- D-galactosaminidase. This suggested that carbohydrate, and specifically the Gal beta (1----3)GalNAc disaccharide, formed an integral part of the epitopes of most of the antibodies. The isolated disaccharide, however, exhibited 250,000 times less inhibitory activity in the competitive binding assay than epiglycanin. The binding capacity of epiglycanin was also reduced by incubation with trypsin or pronase, suggesting a high molecular weight dependency for binding. Incubation with sialidase increased its affinity for the antibodies. The binding of the antibodies to epiglycanin was strongly inhibited by peanut agglutinin, and to a lesser extent by lectins from Triticum vulgaris, Ricinus communis, Pisum sativum and Phaseolus vulgaris. None of the antibodies bound to any of eight different gangliosides immobilized on HPTLC plates. Mono- (Fab) and divalent [F(ab')2] fragments of the antibodies possessed very low affinity for epiglycanin. The results demonstrated that the specificities of the antibodies are related, but distinguishable, and they suggest that this epiglycanin-IgM model may be useful for studies on the general principles of the interaction between IgM antibodies and mucin-type glycoproteins.
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PMID:Development and characterization of monoclonal antibodies against a mucin-type glycoprotein. 149 19

Peptido-keratan sulphate fragments were isolated from the nucleus pulposus of bovine intervertebral discs (2-year-old animals) after digestion with chondroitin ABC lyase followed by digestion with diphenylcarbamoyl chloride-treated trypsin of A1D1 proteoglycans and gel-permeation chromatography on Sepharose CL-6B. The peptido-keratan sulphate fragments were subjected to alkaline borohydride reduction. The reduced chains were treated with keratanase in the presence of the sialidase inhibitor 2,3-dehydro-2-deoxy-N-acetylneuraminic acid, and the digest was subjected to alkaline borohydride reduction. This produced oligosaccharides with galactitol at their reducing ends. This reduced digest was chromatographed on a Nucleosil 5 SB anion-exchange column and individual oligosaccharides were isolated. One of these was shown by 600 MHz 1H-n.m.r. spectroscopy to have the following structure: NeuAc alpha 2-6Gal beta 1-4GlcNAc(6-SO4)beta 1-3Gal-ol The structure of this oligosaccharide shows that keratan sulphate chains from bovine intervertebral disc have non-reducing termini with N-acetylneuraminic acid linked alpha(2----6) as well as alpha(2----3) to an unsulphated galactose.
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PMID:Skeletal keratan sulphate chains isolated from bovine intervertebral disc may terminate in alpha(2----6)-linked N-acetylneuraminic acid. 154 Jan 42

Immunoblotting with two examples of anti-Dha to the electrophoretically separated components of antigen-positive membranes gave a positive reaction with a component of the same apparent Mr (40,000) as sialoglycoprotein beta (SGP beta, syn: glycoconnectin, glycophorin C). The Dha antigenic determinant was sensitive to trypsin, but resistant to chymotrypsin and Endo F. By immunoblotting, one anti-Dha failed to react with sialidase-treated Dh(a+) cells, whilst the other gave a positive result. In contrast, neither antibody agglutinated sialidase-treated red cells. SGP beta was precipitated from Dh(a+) and Dh(a-) phenotype red cells by monoclonal anti-beta (NBTS/BRIC 10). SGP beta from Dh(a+) but not from Dh(a-) red cells was stained by immunoblotting with anti-Dha. These results assign the Dha antigenic epitope to SGP beta.
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PMID:Immunochemical characterisation of the low-incidence antigen, Dha. 171 1

Sialophorin (CD43) is the major surface mucin on many hematopoietic cells. It has been implicated in regulating the survival of T lymphocytes in the circulation, and its functions in vitro as the receptor of a T lymphocyte and monocyte activation pathway. The structure of CD43 was examined by protease treatment of lymphoblastoid cells bearing surface CD43. Trypsin treatment converts CD43 (apparent Mr 115,000) to species of apparent Mr 100,000 called T-100, which remains cell-associated; however, the mechanism of trypsin action was not clarified. Pancreatic elastase and Staphylococcus aureus V8 protease cleave CD43 at discrete extracellular sites. V8 protease generates two fragments, which together account for all properties and mass of the parent molecule. The COOH-terminal fragment V-90 (apparent Mr 90,000) consists of the intracellular and transmembrane regions and part of the extracellular region. The fragment V-30 (apparent Mr 30,000), which is released from the cell, comprises the NH2-terminal approximately 78 amino acids with attached oligosaccharides. V-30 contains the binding sites for the antibodies L2 and L10; the latter is the antibody that activates lymphocytes and monocytes. These findings subdivide the extracellular region of CD43 and indicate that the activation-inducing epitope is located in the most distal portion of the molecule. It is shown that CD43 is insensitive to all but very high concentrations of three proteases. Pretreatment with sialidase enhances sensitivity 13-fold for trypsin, 40-fold for S. aureus V8 protease, and 400-fold for elastase, suggesting that sialic acid influences the survival of surface CD43 molecules when cells are exposed to protease.
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PMID:Proteolytic fragmentation of sialophorin (CD43). Localization of the activation-inducing site and examination of the role of sialic acid. 223 Jan 23

Human anti-S and anti-s eluates bound to glycophorin B on immunoblots from membranes of S+ and s+ red cells, respectively. Eluates of human anti-S were more efficiently prepared from sensitized trypsin-treated cells than from sensitized untreated cells. The results of immunoblotting membranes from enzyme-treated cells confirmed the serological findings: S and s antigens were not affected by treatment with trypsin or sialidase but were destroyed or much depressed by treatment with papain, pronase or alpha-chymotrypsin. Immunoblotting with anti-S or anti-s of membranes from cells with unusual MNS phenotypes confirms the involvement of glycophorin B in hybrid glycophorins; the existence of such hybrid glycophorins was deduced previously from serological work or immunoblotting with monoclonal antibodies. The presence of s-active glycophorin B in glycophorin (B-A)Dantu, in glycophorin BMiIII and in glycophorin (A-B)MiV was confirmed. The bands observed when Mit+ membranes were immunoblotted with anti-S supports the suggestion from serological work that the Mit antigen is associated with an altered S antigen.
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PMID:Immunoblotting of human red cell membranes: detection of glycophorin B with anti-S and anti-s antibodies. 239 72

The IgG2a monoclonal antibody TH-1, which reacts specifically with blood group A1 but with neither A2 nor O erythrocytes, has been established. The antibody reacted only with A1 erythrocytes in hemagglutination and antibody absorption assays; it did not react with A2 erythrocytes, even after trypsin or sialidase treatment. This antibody detected, on TLC immunostaining, a series of glycolipids from A1 erythrocytes but virtually none or very weak bands from A2 erythrocytes. It did not react with type 1 or type 2 chain A, or with globo-A. The simplest reactive component was isolated from a previously assigned Ab fraction by HPTLC of acetylated compounds. The structure of the reactive component was characterized by 1H NMR spectroscopy, methylation analysis, and enzymatic degradation, as shown below: (Formula: see text). The structure is essentially a repetitive A epitope attached to type 2 chain and is hereby called type 3 chain A. The determinant can be carried on extended and/or branched structures, but it was not detectable in glycoproteins. The structure was characteristic of A1 erythrocytes and present in only trace amounts in A2 erythrocytes. The precursor H (Fuc alpha 1----2Gal beta 1----3GalNAc alpha 1----3[Fuc alpha 1----2]Gal beta 1----4GlcNAc beta 1----R; type 3 chain H) was present in greater quantity in A2 erythrocytes than in A1 erythrocytes, but it was absent in both O and B erythrocytes. The A1 transferase apparently can transfer alpha-GalNAc to type 3 chain H, while the A2 transferase may not have this ability.
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PMID:Repetitive A epitope (type 3 chain A) defined by blood group A1-specific monoclonal antibody TH-1: chemical basis of qualitative A1 and A2 distinction. 257 90


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