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)

Unbound bovine secretory component was cleaved into two-domain and one-domain fragments by trypsin within 1 h. Bovine secretory component covalently bound to bovine IgA dimer, as in secretory IgA, was much more resistant to fragmentation, which did not proceed beyond the three-domain stage even after 5 h. Bovine secretory component non-covalently bound to bovine IgM or to human IgM or IgA polymer was also relatively resistant to fragmentation, which again was largely arrested at the three-domain stage. A model for the binding of secretory component to polymeric immunoglobulin is proposed.
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PMID:Differences in fragmentation between bound and unbound bovine secretory component suggest a model for its interaction with polymeric immunoglobulin. 405 23

The susceptibility of exocrine and serum immunoglobulins and antibodies to proteolytic degradation was assessed. Colostral and duodenal fluid exocrine 11S IgA, monomeric serum IgA, and IgG were digested with trypsin, chymotrypsin, or duodenal fluid. Exocrine IgA was more resistant to digestion than were the serum immunoglobulins. Under conditions of the experiments, most of colostral IgA retained its 11S quaternary structure, including the secretory piece; the portion degraded was reduced almost entirely to peptides. The superior resistance of exocrine IgA was also demonstrated by digestion of serum IgG and nasal exocrine IgA diphtheria antitoxins with trypsin or duodenal fluid. Selective precipitation of trypsin-digested antitoxins with antibodies to heavy chains, light chains, or secretory piece revealed that the differences in susceptibility to digestion were due to differences in lability of the Fc portions of the IgA and IgG antibody molecules. The Fc portions of IgG antibody molecules were degraded or cleaved from the Fab units of the molecules, whereas the Fc-like portions of IgA antibody molecules remained associated with their Fab-like units and the secretory piece. On the other hand, trypsin treatment did not affect the antigen binding ability of the Fab parts of either the exocrine IgA or IgG antibodies. The Fc-like portions of exocrine IgA may be protected from tryptic degradation by the quaternary structure of the 11S molecules, which includes a dimer of 7S IgA subunits and the secretory piece.
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PMID:Proteolytic degradation of exocrine and serum immunoglobulins. 419 90

The function of human purified colostral and gastrointestinal IgA has been studied by its ability to agglutinate common gastrointestinal organisms. Agglutinating activity was unaffected by trypsin or acid but it was abolished rapidly by pepsin. Both colostral and gastrointestinal IgA agglutinated a wide range of enteric organisms. Variations in this activity occurred between different individuals, and between different gastrointestinal sites in the same individual. In preliminary studies, saliva and IgA prepared from gastric and jejunal secretions in patients with pernicious anaemia showed a more uniform agglutination pattern than IgA prepared from the same sites in other patients. The agglutinin activity of IgA prepared from a particular site may be determined by the bacterial flora at that site. Agglutination methods for assessing the function of gastrointestinal antibody may be of value in the study of the possible roles of antibodies in inflammatory bowel disease.
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PMID:Bacterial agglutination studies with secretory IgA prepared from human gastrointestinal secretions and colostrum. 455 7

The serum of a patient (L'ec) with an IgM lambda monoclonal protein was noted to bind albumin on immunoelectrophoresis. Analytical ultracentrifugation of the L'ec serum demonstrated 23S and 12S peaks, but no 4S (albumin) boundary. Immunologically identical 20S and 9S IgM proteins were isolated from the serum and the addition in vitro of either the patient's albumin or albumin isolated from normal serum was shown to reconstitute the 23S and 12S boundaries. The binding of high molecular weight IgM to albumin was demonstated by Sephadex G200 chromatography with (125)I-labeled albumin and isolated IgM. Immunoelectrophoresis of the L'ec IgM developed with aggregated albumin (reverse immunoelectrophoresis) also demonstrated the binding of albumin to IgM. That all of the patient's IgM complexed with albumin was shown by affinity chromatography employing an aggregated albumin-immunoadsorbent column. Binding was shown to be of the noncovalent type by polyacrylamide gel electrophoresis in 8 M urea. With hot trypsin proteolysis, Fabmu and Fcmu5 fragments were isolated, and monomer albumin was shown to complex only with the Fabmu fragment by both analytical ultracentrifugation and molecular sieve chromatogaphy employing (125)I-labeled Fab fragments. 1 mol of Fabmu fragment bound 1 mol of monomer albumin. Polymers of human albumin, produced by heat aggregation, precipitated with the isolated L'ec protein on gel diffusion analysis and, when coated on sheep red blood cells, gave a hemagglutination titer greater than 1 million with the whole L'ec serum. 50 additional monoclonal IgM, 33 IgA, and 80 IgG sera failed to show precipitation or hemagglutination with aggregated albumin. Native monomer albumin inhibited precipitation only at high concentrations (> 50 mg/ml); dimer albumin or fragments of albumin produced by trypsin digestion inhibited at low concentrations (0.4 mg/ml). No reactivity occurred with the albumin of five other mammalian species, including bovine. The L'ec protein has the characteristics of an antibody against aggregated albumin, which also has reactivity with native (monomer) albumin. This system shares many similarities with the reaction of IgM human rheumatoid factors with IgG antigen.
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PMID:A monoclonal IgM protein with antibody-like activity for human albumin. 485 63

Components were solubilized from human glomerular basement membrane by digestion with collagenase and pepsin or by extraction with guanidine-HCl either directly or after previous digestion with the enzyme. The diverse preparations were used as antigens in the enzyme-linked immunosorbent assay (ELISA) of antibody titers in sera from patients with Goodpasture syndrome and patients with other forms of glomerulonephritis, that is, systemic lupus erythematosus, periarteritis nodosa, and IgA-related nephropathy. Patients with Goodpasture syndrome had high titers of IgG antibodies reacting most strongly with collagenase digests. The antigen(s) was only partly solubilized by guanidine-HCl extraction, was destroyed by pepsin digestion as well as reduction, and partly destroyed by trypsin digestion. The antigen(s) is most likely noncollagenous protein. Antibodies from patients with other forms of nephritis were directed primarily against antigens in guanidine-HCl extracts, while the antigen(s) was not solubilized by collagenase digestion. Pepsin digestion destroyed the antigen(s). The antibodies were of a different class, that is, the patients with systemic lupus erythematosus had IgG and IgA as well as IgM antibodies; the patients with periarteritis nodosa had IgM or IgG and IgA antibodies, while the patients with IgA-related nephritis had the highest recorded titers of IgA but also had IgG as well as IgM antibodies. None of the patients had antibodies directed against triple helical collagen. The antibody response in anti-GBM antibody-related nephritis, then, is different both with respect to antigen and antibody class and depends on the underlying disease syndrome.
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PMID:Antiglomerular basement membrane antibody: antibody specificity in different forms of glomerulonephritis. 613 25

Formalin is known to mask the antigenicity of immune deposits in glomeruli but not of surface immunoglobulins of isolated lymphocytes. We have shown in mice with experimental passive anti-GBM glomerulonephritis that formalin masks the antigenicity of GBM-bound immunoglobulins only if the tissue is fixed before sectioning. The presence of a high concentration of normal bovine serum during fixation of cryostat sections masks the antigenicity of immune deposits, whereas formalin alone has no obvious effect. The same results were obtained with human immunoglobulins (IgG, IgM and IgA) bound to tissue sections. Protease treatment with pepsin and trypsin restored the ability of the immunoglobulins to be stained. The masking effect seems to be due to extensive cross-linking of environmental proteins which prevents fluorescent conjugates reaching their antigens. Methods for detecting immunoglobulins in tissues must, therefore, take into consideration the influence of fixatives not only on epitopes but also on the environment in which the antigenic determinants are localised.
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PMID:Detection of immune deposits in glomeruli: the masking effect on antigenicity of formalin in the presence of proteins. 616 39

To characterize the Fc receptors on rat alveolar and peritoneal macrophages (M phi), we analyzed their ability to form rosettes with fixed ox erythrocytes (Eo') coated with myeloma proteins of all rat Ig classes and with fresh erythrocytes (Eo) sensitized with rat IgG1 and IgG2, rabbit IgG and IgM, and mouse IgA antibodies. The M phi formed rosettes with Eo' coated with rat myeloma proteins of classes IgG1, IgG2a, IgG2b, and IgE but not IgG2c, IgA, IgM, and IgD. Rat M phi also formed rosettes with Eo' coated with human IgG1, IgG3, IgG4, mouse IgG1, IgG2a, IgG2b, and rabbit IgG. Furthermore, rat M phi formed rosettes with Eo sensitized with rat IgG1, IgG2, or rabbit IgG antibodies but not with Eo sensitized with rabbit IgM or mouse IgA antibodies. Trypsin treatment of rat M phi abolished IgG1/IgG2b and IgE but not IgG2a rosettes. The IgG2a and IgE rosettes were Ig class specific because they were inhibited only by rat IgG2a and rat IgE, respectively. In contrast, IgG1 and IgG2b rosettes were inhibited equally by IgG1 and IgG2b. Heterologous IgG inhibited IgG1/IgG2b but not IgG2a rosettes. Rat IgE inhibited rat IgG1, IgG2b, and heterologous IgG rosette formation on rat M phi. Although Eo' coated with rat IgE formed rosettes with mouse P388D1 macrophagelike cells, rat IgE did not inhibit IgG rosettes on these cells. Similarly, Eo' coated with human IgE formed rosettes with human U937 macrophage-like cells, but human IgE did not inhibit IgG rosettes on these cells. The results indicate that rat M phi have at least three distinct Fc receptors: one is specific for rat IgG2a and is trypsin resistant; a second is specific for rat IgE and is trypsin sensitive; and a third reacts with rat IgG1 rat IgG2b, and heterologous IgG and is trypsin sensitive. Rat IgE inhibited IgG1/IgG2b rosettes undirectionally and uniquely on rat M phi.
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PMID:Specificity of fc receptors for IgG2a, IgG1/IgG2b, and IgE on rat macrophages. 616 53

Secretory IgA (sIgA) and monomeric IgA (mIgA) were purified from normal rat bile, and their role in the gastrointestinal tract was investigated. Biliary sIgA has a molecular weight of approximately 400,000 daltons and a sedimentation constant of 11.7S. Thus, sIgA obtained from rat bile had physicochemical properties similar to those reported for sIgA in other secretions, and probably consists of L-chains, alpha-chains and secretory component. After in vitro incubation with trypsin or intestinal fluid, sIgA remained intact, whereas mIgA was hydrolyzed. Rats challenged repeatedly with dinitrophenylated bovine serum albumin (DNP-BSA) had specific IgA antibody against DNP in the bile and feces as measured by a radioimmunoassay using [3H]-DNP-lysine. Our results demonstrate a possibility that biliary sIgA, not mIgA, has an important role which inhibits the absorption of foreign antigen from intestine.
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PMID:Property and physiological role of biliary secretory IgA in rats. 618 5

alpha 2-macroglobulin is probably the most important of the antiproteases in plasma. In this study, the relationships of plasma alpha 2-macroglobulin to the clinical features of acute pancreatitis as well as to plasma levels of other antiproteases, immunoglobulins, and immunoreactive trypsin, were investigated in 55 patients with acute pancreatitis. The mean level of alpha 2-macroglobulin in 395 plasma samples from the patients was 2.12 g/liter compared with 2.41 g/liter in 29 healthy subjects and 2.93 g/liter in 17 patients with septicemia. Plasma levels were lower in 12 patients with severe pancreatitis than in 43 with mild attacks, and the lowest levels in three fatal attacks were less than half the mean of the normal range. Lowest levels were recorded at a mean time of 3 days after admission in the patients with mild attacks, at 5 days after admission in the patients with severe attacks, and 9 days after admission in those with fatal attacks. In contrast, plasma levels of the alpha 1-proteinase inhibitor antichymotrypsin and C-reactive protein increased to above normal levels during the attack, significantly more so in severe compared with mild attacks. Plasma levels of IgA, IgG, and IgM remained within the normal range or were increased. In patients with severe pancreatitis, plasma levels of immunoreactive trypsin remained elevated for longer than in those with mild attacks although there was little initial difference in the levels. These data suggest that decreasing levels of alpha 2-macroglobulin during the course of acute pancreatitis are due to a specific mechanism and unrelated, for the most part, to any generalized effect of pancreatitis on protein synthesis. The formation of rapidly cleared complexes between alpha 2-macroglobulin and active proteases is the most tenable explanation for the depletion of plasma levels, but the clinical significance of the changes remains unclear.
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PMID:Relation of alpha 2-macroglobulin and other antiproteases to the clinical features of acute pancreatitis. 619 93

To clarify the co-expression phenomenon of T-cell Fc receptors (FcR) specific for different isotypes on the clonal level, a murine hybridoma clone T2D4 was studied. T2D4 cells originally reported to bear FcR for IgG (Fc gamma R) and to release a Fc gamma R-related T-cell factor binding to IgG (immunoglobulin binding factor; IBF) proved to have also the receptor for IgA. The binding of IgA was detected by rosette formation with trinitrophenylated ox red blood cells (TNP-ORBC) after preincubation of T2D4 cells with MOPC 315 IgA having anti-TNP activity, or directly with TNP-ORBC sensitized with MOPC 315 IgA. While the binding of MOPC 315 IgA was competed for by IgA but not by IgG2A nor IgG2B, IgA failed to inhibit the rosette formation of the cells with ORBC sensitized with rabbit IgG antibody (EA ox gamma), proving that T2D4 cells express FcR specific for IgA (Fc alpha R) in addition to Fc gamma R. Co-expression of both receptors on the same cell surface was demonstrated by a double rosette technique using TNP-quail red blood cells (TNP-QRBC) and EAox gamma. Fc alpha R activity of the cells was completely abrogated by 15 min. incubation with 0.1 mg/ml trypsin, whereas Fc gamma R was resistant even to 1 mg/ml trypsin. The expression of Fc alpha R was augmented (up-regulation) by IgA at the concentration above 300 micrograms/ml and inhibited (down-regulation) by 1000 u./ml of murine beta-interferon (beta-IFN). Conversely, the expression of Fc gamma R was down-regulated by IgA and up-regulated by alpha-IFN. Thus, Fc gamma R and Fc alpha R are co-expressed and reciprocally regulated on these cell lines. The possible co-production of IBF and the Fc alpha R-related binding factor specific for IgA is discussed.
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PMID:T-cell hybridoma co-expressing Fc receptors for different isotypes. I. Reciprocal regulation of Fc alpha R and Fc gamma R expression by IgA and interferon. 621 65


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