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)

Soya, in spite of its high nutritional value and moderate cost, possesses certain undesirable qualities which limit its use in animal and human nutrition. The amendment of these qualities has resulted in much work. In this study the effects of technological treatments on the properties of certain protein fractions capable of being produced industrially were observed. Three fractions were prepared from defatted soybean flour of the "Harosoy 63" variety: an acid-precipitated fraction, a cold-insoluble fraction at 0-3 degrees C, and a water-soluble fraction. The properties of the fractions were studied both before denaturation and after denaturation by either heat or alcohol. The degree of proteolysis of each fraction by two digestive enzymes, pepsin and trypsin, was measured by the increase of non-protein nitrogen as a function of time. Several methods were used for electrophoretic analysis. The results showed that the thermal treatment at 100 degrees C and the treatment with varying concentrations of ethanol (from 10 to 100 p. 100) modified electrophoretic diagrams and the solubility of the proteins in trichloracetic acid. Moderate, moist heating of the protein fractions (100 degrees C, 20 mn) before proteolysis by pepsin and trypsin, in general, favored proteolysis. The most marked effect observed was in the acid-precipitated fraction (in which Kunitz inhibitor was concentrated treated by trypsin. Heating the fractions beyond thirty minutes had a negative effect on proteolysis: the level of proteolysis was the same, or in some cases, lower than before denaturation, especially on subsequent treatment with pepsin. The effects of the ethanol treatment were different from that of heat: the proteolysis was accelerated only with the acid-precipitated fraction.
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PMID:[Denaturation and enzymatic proteolysis in vitro of protein fractions of soya flour]. 76 45

A large fraction of a constitutively synthesized polypeptide, comprising 5% of the total Escherichia coli protein, is released when plasmolysed cells are subjected to osmotic shock into ice-cold water. Since the protein is not liberated by the conversion of cells to spheroplasts, it is not a typical periplasmic protein. A complex pattern of association with the cell envelope indicates that it is bound to this structure in vivo. Its susceptibility to trypsin and its interaction with specific antibodies vary with the type of preparations used. Based on these observations, we postulate a peripheral location at the inner surface of the plasma membrane. The protein has been purified to homogeneity from osmotic shock fluid. It has a mass of 44 000 daltons. Some of its physical and chemical properties have been investigated. Most remarkable are its strongly aggregating and adhesive characteristics and its precipitation by vinblastine and calcium ions. These unusual properties, its presumed location, and the observation that it is present in large amounts (approximately 70 000 molecules per cell) suggest a structural role for this protein.
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PMID:Properties of a major protein released from Escherichia coli by osmotic shock. 77 20

The heavy water (D2O) has been shown to induce the conformational transitions in trypsin, chymotrypsin and pepsin. The transfer of proteins from H2O into D2O results a change in their sensitivity to UV-light. An increase in sensitivity to the irradiation at 248 nm and a decrease in sensitivity to the irradiation at 280 nm were observed. The quantum yield of chromophore photolysis (for cystyne and tryptophan) is correspondingly changed. However, although the quantum yield of sensitized reduction of cystine by solvated electrons photochemically ejected from the aromatic acid residues during irradiation at 280 nm increases instead of a rise a drop in the quantum yield of protein inactivation is registered. The data obtained are discussed in terms of importance of solvated shell for conformational stability of proteins. The solvated electrons are suggested to be transfered mainly to nonessential disulfide bridges within trypsin molecule. Rupture of these bonds does not result in trypsin inactivation.
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PMID:[Influence of heavy water (D20) on the conformation and UV-sensitivity of proteins]. 80 85

Adenovirus type 5 'cores' prepared by heating in the presence of deoxycholate and partially purified on a glycerol density gradient could be visualized as roughly isometrical particles with a condensed centre from which twisted filaments or loops of DNA emanated. This compact structure was readily dispersed by spreading on distilled water or by treatment with EDTA, Nonidet, DNase or trypsin. Spreading with Nonidet was particularly effective in unfolding the cores and revealing long filaments about 100 A thick presumably of the virus nucleoprotein. Subunits (about 30 to 60 A in diam.) could be seen free in the DNase-treated cores, suggesting a particulate nature of one or both of the core proteins.
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PMID:Electron microscopy of adenovirus cores. 80 87

When Rana cancrivora were collected from fresh water and dehydrated (weight loss 4-10%) by exposure to saline, the plasma titre of hydro-osmotic activity, measured by amphibian bladder assay, was increased three-to fourfold. This activity, which was abolished by thioglycollate and by incubation with tyrosinase or trypsin, was ascribed to vasotocin. The plasma vasotocin activities (hydrated and dehydrated frogs respectively) were estimated to be 0-03-0-5 and 0-15-0-25 mug/1; if referred to oxytocin as a standard the equivalent values were 10 and 30-60 mu./ml. Assuming that the increase represented released pituitary hormone, the amount of vasotocin released by osmotic dehydration was calculated to be of the order of 1 ng. Pituitary glands of hydrated and dehydrated frogs were estimated to have 0.15 and 0-18 mug vasotocin/gland respectively. The possible physiological function of released vasotocin in promoting reabsorption of urea from the urinary bladder is discussed in relation to the euryhaline ability of R. cancrivora.
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PMID:Vasotocin-like activity in the plasms of the euryhaline frog (Rana cancrivora) after transfer from fresh water to saline. 81 47

Water-soluble antigens isolated from acetone-dried, gram-negative bacteria elicited reaginic antibody formation in mice. Antibodies specific for Escherichia coli antigens reacted with antigens isolated from several enterobacterial species tested, but not with antigens isolated from Pseudomonas aeruginosa. Reaginic antibodies induced by antigens isolated from a P. aeruginosa strain reacted with antigens isolated from several P.aeruginosa serotypes as well as with a purified protein component of the envelope of P. aeruginosa. The anti-Pseudomonas reagins did not cross-react with enterobacterial antigens. Antigenicity of the bacterial extracts was destroyed by trypsin treatment and reduced by heating, which suggested that the antigens were protein in nature. Whole bacterial cells adsorbed out reaginic antibodies, indicating that the antigens are located at or near the surface of the bacteria.
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PMID:Reaginic antibody production to protein antigens of Escherichia coli and Pseudomonas aeruginosa by mice. 82 18

The topography of the external surface of the human red cell membrane has been studied using an impermeant radioactive probe, [125I]diazodiiodosulfanilic acid, which binds covalently to protein groups of the membrane following reaction with intact cells. The pattern of labeling was assessed by sodium dodecyl sulfate-polyacrylamide disc gel electrophoresis followed by sequential analysis of single gels for carbohydrates (by staining with the periodic acid-Schiff (PAS) reagent), for proteins (by staining with Coomassie blue), and for radioactivity (by counting gels sliced in 2-mm segments). The radioactive probe bound to membrane polypeptides with apparent molecular weights of 94,200, 58,100, and 46,500 (Peaks A, B, and C, respectively). Peak A co-migrated with a small periodic acid-Schiff-positive band and protein Band 3 (nomenclature of Steck) (Steck, T.L. (1974)J. Cell Biol. 62: 1-19). Peak B migrated with protein Band(s) 4.5 slightly ahead of the major membrane glycoprotein (PAS-1). Peak C migrated like glycoprotein PAS-2 and protein Band 5, the actin-like, water-soluble membrane protein. In contrast to lactoperoxidase iodination and a number of other probes, [125I]diazodiiodosulfanilic acid reacted minimally with the major membrane glycoprotein, glycophorin. When it was reacted with isolated ghosts, all molecular weight classes of polypeptides were labeled. Treatment of labeled cells with neuraminidase or trypsin altered the glycoprotein staining pattern, but not the radioactive peaks. On the other hand, Pronase eliminated the Mr=94,200 radioactive peak, diminished the other two radioactive peaks, and profoundly changed the glycoprotein and protein staining patterns. Treatment of the membranes of labeled cells in a low ionic strength alkaline medium did not alter radioactive peaks and demonstrated that Peak C differed from the actin-like membrane protein. A nonionic detergent, Triton X-100, solubilized all radioactive components. The studies have defined the binding of [125I]diazodiiodosulfanilic acid to external proteins of the human red cell membrane. Its pattern of reaction differs quantitatively and qualitatively from other commonly used reagents, and it provides a useful additional vectorial probe for the study of membrane topography. Its reactions provide further evidence of the organizational complexity of the red cell membrane and emphasize the fact that interpretation of information derived from the use of membrane probes must take into account the differences resulting from the properties of the probing reagents themselves.
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PMID:Topography of the external surface of the human red blood cell membrane studied with a nonpenetrating label, [125I]diazodiiodosulfanilic acid. 83 50

1. A new method for the assay of insect prothoracicotropic hormone (PTTH) is described, using fourth instar larvae of Manduca sexta. Larvae neck-ligated at a critical time to prevent release of PTTH from the head fail to undergo the next larval moult. Such ligated larvae moult to fifth instar larvae or larval-pupal intermediates after injection of brain homogenates from Manduca larvae, pupae or pharate adults. The degree of response is proportional to the concentration of brain homogenate injected. 2. The source of PTTH in the pupal brain is the dorsal region of the protocerebrum containing the lateral neurosecretory cells. Microhomogennates of single pieces of brain showed activity with this method. 3. PTTH activity in partially purified extracts is water soluable, stable to boiling for 10 min, and is destroyed by Pronase or trypsin.
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PMID:Prothoracicotropic hormone in Manduca sexta: localization by a larval assay. 87 Jun 1

Water-soluble poly(N-vinylpyrrolidone) of molecular weight 10 000 was modified by hydrolysis of 5% of the gamma-lactam rings, and formation of the N-hydroxysuccinimidester. This activated polymer was bound covalently to trypsin (EC 3.4.21.4) and chymotrypsin (EC 3.4.21.1) to complexes of a molecular weight of about 150 000. The bound enzymes showed an increase in stability towards autolysis. Towards small molecular weight substrates the trypsin-poly (N-vinylpyrrolidone) conjugate showed an increase in specific activity of 1: 1.6, whereas the activity towards larger substrate was found to be only 20%. Chymotrypsin-poly(N-vinylpyrrolidone) showed decreased activity against small (50%) and large (7%) molecular weight substrates.
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PMID:Preparation and properties of trypsin and chymotrysin coupled covalently to poly (N-vinylpyrrolidone). 88 41

Partial enzymatic hydrolysis of whey protein by trypsin increased solubility of this protein in water. Water-insoluble, heat-denaturated whey protein was solubilized fully by trypsinization. Optimal conditions for the enzyme reaction, established by the pH-stat technique, were: digestion at pH 8.0 and 55 C for approximately 3 h, at an enzyme-substrate ratio of 1 : 100. Under these conditions, 500 mumoles of titratable protons were liberated per g of substrate in the course of the reaction. Digestion at 40 C generated only about 400 mumoles of acid. Predenaturation of the substrate by heat did not improve digestibility. The extent of hydrolysis reached approximately 8% of all peptide bonds in the protein. Fractionation of the digest on Sephadex G-50 showed it was composed of a major fraction of highly water soluble peptides, ranging in molecular weight from approximately 500 to 5000. The gel excluded a minor fraction of larger, aggregated peptides. This aggregate was dissociated in the presence of urea and a reducing agent. All amino acids in the digest, except some lysine and arginine, were peptide bound.
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PMID:Partial enzymatic hydrolysis of whey protein by trypsin. 91 66


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