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 water-soluble dye 6-carboxyfluorescein was trapped in the internal aqueous compartments of small sonicated dioleoyl lecithin vesicles and used to assess the kinetics of transfer of vesicle contents to human lymphocytes. By using flow microfluorometry, the initial rate of dye transfer to the cells was measured as a function of the concentration of vesicles in the external medium. The rate of transfer consists of at least two components, one of which saturates at high vesicle concentration and the other of which does not saturate in the range of concentrations explored. The saturable component was competitively inhibited by vesicles not containing dye. Both the saturable and nonsaturable components of transfer were inhibited by fetal calf serum or bovine serum albumin but neither component was affected by bovine IgG, choline chloride, or heparin. Pretreatment of the lymphocytes with trypsin or Pronase had no effect on either component. The saturable component can be interpreted in terms of a two-step process in which vesicles bind reversely to sites on the cell surface, and dye is then transferred into the cell from the vesicle-site complex.
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PMID:Liposome--lymphocyte interaction: saturable sites for transfer and intracellular release of liposome contents. 27 88

The concanavalin A (Con A)-induced agglutinability of normal, preneoplastic, and neoplastic mouse mammary epithelial cells was examined. Cells freshly dissociated from normal mammary glands, hyperplastic alveolar nodules, or primary mammary adenocarcinomas by collagenase digestion in the presence of bovine serum albumin were strongly agglutinated by low concentrations of Con A. After short-term culture in vitro, however, cells from all three types of tissue were only weakly agglutinated by Con A, as measured by both suspension and hemadsorption assays. By comparison, cells of three established mammary tumor culture lines agglutinated strongly in the presence of the lectin. Treatment of the normal, preneoplastic, and neoplastic mammary cells in primary cultures with either trypsin or collagenase had little or no effect on their agglutinability, whereas hyaluronidase significantly increased their reactivity. Studies with fluorescein-tagged Con A indicated that all three cell types were capable of binding the lectin. The results were consistent with previous evidence suggesting that neoplastic transformation of mouse mammary epithelial cells is not manifested in vitro by several of the alterations in growth patterns, intercellular interactions, and surface properties that usually accompany transformation of fibroblastic cells.
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PMID:Concanavalin A-induced agglutinability of normal, preneoplastic, and neoplastic mouse mammary cells. 28 51

A stable variant of a clone of the P388D1 macrophage line was isolated using four cycles of treatment with mouse IgG2a-rabbit anti-kappa complexes and rabbit complement. The variant had the same Ka and about the same number of sites per cell for IgG2a as the parent line. However, the variant had 10% as many binding sites for rabbit IgG in soluble antigen-antibody complexes, and the affinity of binding was threefold higher. This change in binding of complexes to cells of a cloned line without alternation of IgG2a binding provides evidence for the presence of two distinct Fc receptors. The two receptors could also be distiguished on the P388D1 line and on thioglycollate-induced mouse peritoneal macrophages by differential sensitivity to trypsinization. The receptors that bind monomeric IgG2a, sheep erythrocytes (SRBC) covalently bound with IgG2a or rabbit IgG using glutaraldehyde, and Sephadex beads coupled with IgG2a or rabbit IgG using cyanogen bromide activitation, is sensitive to trypsinization. The receptor that binds soluble rabbit antibody-antigen complexes, trinitrophenyl-SRBC and dinitrophenyl(DNP)-bovine serum albumin Sephadex beads coated with rabbit anti-DNP IgG is trypsin resitant, the observation that uncomplexed rabbit IgG oes not bind to the trypsin-resistant receptor, whereas the same IgG bound to its antigen does, suggests that conformational changes induced by the binding of ligand may be of consequence in macrophage function.
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PMID:The presence of two Fc receptors on mouse macrophages: evidence from a variant cell line and differential trypsin sensitivity. 32 99

Heat-stable enterotoxin (ST) produced by porcine strains of enterotoxigenic (ENT+) Escherichia coli has been purified to apparent homogeneity by sequential ultrafiltration, acetone fractionation, preparative gel electrophoresis, diethylaminoethyl Bio-Gel A ion-exchange chromatography, and Bio-Gel P-10 gel filtration. The enterotoxin, purified more than 1,500-fold, exhibited a molecular weight of 4,400, as determined by both sodium dodecyl sulfate-gel electrophoresis and gel filtration. A molecular weight of 5,100, representing 47 residues, was calculated from amino acid analysis data. The amino acid content was distinctive, with an unusually high proportion of cystines and few hydrophobic amino acids. A single amino-terminal residue, glycine, was observed. Purified ST was stable to heating (100 degrees C, 30 min) and did not lose biological activity after treatment with Pronase, trypsin, proteinase K, deoxyribonuclease, ribonuclease, and phospholipase C. Periodic acid oxidation and several organic solvents (acetone, phenol, chloroform, and methanol) had no effect on the biological activity of ST. Further, purified ST was stable to acid treatment at pH 1.0 but lost biological activity at pH values greater than 9.0. Neither lipopolysaccharide nor lipid contamination was evident in purified preparations. A characteristic absorption spectrum was observed during the course of the purification, which shifted from a maximum at 260 nm in crude preparations to 270 nm for the purified toxin. Antiserum obtained from rabbits immunized with ST or ST coupled to bovine serum albumin neutralized the action of the enterotoxin in suckling mice; however, passive hemagglutination and hemolysis titer assays suggested that ST is a poor antigen.
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PMID:Purification and chemical characterization of the heat-stable enterotoxin produced by porcine strains of enterotoxigenic Escherichia coli. 34 81

Macroporous glasses with pore sizes from 400-1000 A appropriate for protein binding were produced and characterized by a thermal demixing procedure and alkaline after treatment. To achieve a covalent binding capacity relative to proteins, the gamma-aminopropyl derivative was allowed to react with 4-maleinimido benzoylic chloride to give preparations containing, in addition to maleinimide residues, acid chloride structures for the protein binding. A preparation of 400 A pore size was tested for its protein binding capacity relative to bovine serum albumin and trypsin. Furthermore, the capacity of binding glucoamylase from Endomycopsis bispora in active form was studied.
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PMID:[Immobilization of proteins on macroporous glasses involving maleinimide as the anchoring group]. 34 50

The direction of discharge of the nascent peptides of NADPH-cytochrome c reductase and cytochrome b5 from bound polyribosomes of rough microsomes was investigated in order to elucidate the mechanism of separation of these membrane proteins from secretory proteins, which are also synthesized by the same class of ribosomes of rough endoplasmic reticulum. The nascent peptides of NADPH-cytochrome c reductase and cytochrome b5 in intact rough microsomes were accessible to externally added 125I-Fab's against these proteins, and were susceptible to trypsin digestion, whereas the nascent peptides of serum albumin were not. The nascent peptides of these two microsomal proteins were released into the cytoplasm by puromycin treatment of intact rough microsomes, while the nascent peptides of serum albumin were retained in the microsomal lumen. These observations suggest that the nascent peptides of microsomal proteins, which are present on the cytoplasmic surface of the endoplasmic reticulum membrane, are exposed on the surface of microsomal vesicles, while those of secretory proteins are enclosed inside the vesicles. Therefore, the topographical separation of microsomal membrane proteins from secretory proteins is accomplished at the step of their synthesis by the bound polyribosomes of rough endoplasmic reticulum.
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PMID:Biogenesis of endoplasmic reticulum membrane in rat liver cells. II. Discharge of the nascent peptides of NADPH-cytochrome c reductase and cytochrome b5 on the cytoplasmic side of the endoplasmic reticulum membrane. 41 27

Factors that promote oropharyngeal colonization of seriously ill patients with gram-negative bacilli are as yet poorly understood. In this investigation, 34 subjects who required intensive care were studied; 18 (53%) were colonized with gram-negative bacilli. Oropharyngeal epithelial cells of all colonized patients contained adherent bacilli. Fewer alpha-hemolytic streptococci but greater numbers of Pseudomonas aeruginosa and Klebsiella pneumoniae (P less than or equal to 0.01) adhered in vitro to buccal epithelial cells from colonized patients than to cells from noncolonized patients. Adherence of bacilli to buccal cells was inhibited in vitro by concanavalin A but not by bovine serum albumin or phytohemagglutinin. Brief exposure of buccal cells to trypsin increased adherence of bacilli. Prior adherence of one species of bacilli inhibited subsequent adherence of a second species. These findings suggested that epithelial cells of the upper respiratory tract contain binding sites for gram-negative bacilli. Factors associated with serious illness appear to increase the availability of these binding sites, thus facilitating colonization of the upper respiratory tract with gram-negative bacilli.
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PMID:Association of respiratory tract colonization with adherence of gram-negative bacilli to epithelial cells. 44 93

The binding isotherms of native bovine serum albumin with cationic detergents, such as octyl, decyl, dodecyl and tetradecylpyridinium bromides were determined at pH 6.8 and 3.4 at 25 degrees C. The isotherms for dodecyl and tetradecylpyridinium bromides were also determined at 3 degrees C. The average number of detergent cations bound increased with increasing hydrocarbon chain length. At low detergent concentration the binding of all alkylpyridinium bromides was smaller at pH 3.4 than at pH 6.8. Dodecylpyridinium bromide was bound to native beta-lactoglobulin, aldolase, ovalbumin, haemoglobin, myoglobin, lysozyme, trypsin and ribonuclease at pH 6.8. No binding occurred to alpha-chymotrypsin and chymotrypsinogen. The free enthalpy change, --delta G degrees, calculated from intrinsic association constants K was determined.
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PMID:Protein-cationic detergent interaction. Equilibrium dialysis study of the interaction of bovine serum albumin and other proteins with alkylpyridinium bromide. 49 43

Fourier transform infrared and laser Raman spectroscopies were used to study the effects of dodecylpyridinium bromide on the conformation of haemoglobin, myoglobin, bovine serum albumin, ribonuclease, ovalbumin, lysozyme, trypsin and beta-lactoglobulin in aqueous solution. Addition of the cationic detergent caused a decrease in alpha-helix conformation in highly helical proteins. At low detergent concentrations stabilization of beta-sheet conformation was observed.
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PMID:Protein-cationic detergent interaction. Fourier transform infrared and laser Raman spectroscopic studies on the interaction between proteins and dodecylpyridinium bromide. 49 44

Tryptic action occurs when a layer of bovine serum albumin adsorbed on a nickel-plated slide and protected by a Formvar membrane 120 A thick is treated with dilute trypsin solution. But experimental evidence indicates that the trypsin molecules to not cross the membrane. Thus the proposal that trypsin can exert its enzymatic action without intimate contact with the substrate, first set forth in 1948 but later abandoned in favor of a "forced diffusion" hypothesis, now appears the correct interpretation. Analogously, antibodies can be specifically immobilized on one side of a membrane separating them from adsorbed antigens located on the other side.
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PMID:Tryptic action across a membrane. 54 33


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