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 largest fragment produced by complete cyanogen bromide digestion of the alpha chain of human fibrinogen contains 236 residues and has a calculated molecular weight of 23,949. The complete amino acid sequence of the fragment was determined by the isolation of peptides generated by plasmin, trypsin (including digestion of citraconylated material), staphylococcal protease, and chymotrypsin. In addition, some key subfragmentation was achieved by selective chemical cleavage at tryptophan residues. The fragment has an unusual amino acid composition, more than half of its residues being glycine, serine, threonine, and proline. There are very few nonpolar residues, although 7 of the alpha-chain's 10 tryptophans occur in this fragment. The fragment contains 2 cysteine residues located 30 residues apart which are connected by an intrachain disulfide bond in the native molecule. The tryptophans occur with a definite periodicity that highlights a series of 13-residue homology repeats. The fragment also contains the two principal alpha-chain cross-linking sites.
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PMID:Amino acid sequence studies on the alpha chain of human fibrinogen. Complete sequence of the largest cyanogen bromide fragment. 51 44

Oxidation of methionine residues of chicken ovoinhibitor with N-chlorosuccinimide resulted in a selective loss of its inhibitory activities. While trypsin inhibiting activity was not affected at all, half of the chymotrypsin-inhibiting activity and all of the elastase inhibiting activity were lost. Electrophoretic and affinity chromatography studies indicated that the 50% loss of the chymotrypsin-inhibiting activity resulted from the inactivation of one of its two chymotrypsin-inhibiting sites rather than from a decrease in the binding constants of both sites. Oxidation of ovoinhibitor-chymotrypsin and ovoinhibitor-elastase complexes with excess of N-chlorosuccinimide indicated that the complex formation in each case protected the site that binds the enzyme which participated in the complex, but did not protect the site that binds the other enzyme. Quantitative estimation of the number of oxidized methionine residues in the ovoinhibitor isolated from the complexes has shown that in each complex about one methionine residue was protected from oxidation. Nitrophenyl-sulfenylation of the single tryptophan residue of ovoinhibitor did not affect its inhibitory activities at all.
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PMID:Effect of oxidation of methionine residues in chicken ovoinhibitor on its inhibitory activities against trypsin, chymotrypsin, and elastase. 55 34

Intraduodenal amino acids are known to stimulate the release of gastric inhibitory polypeptide and cholecystokinin. In order to separate and quantitate gastric inhibitory polypeptide secretion selectively, 12 normal subjects received an intraduodenal perfusion of a mixed amino acid solution (158 mM) containing either methionine, phenylalanine, tryptophan, and valine (perfusate 1), or an amino acid solution containing arginine, histidine, isoleucine, leucine, lysine, and threonine (perfusate 2). Serum concentrations of gastric inhibitory polypeptide and insulin were significantly greater in the group receiving perfusate 2 (P less than 0.001). In contrast, after administration of amino acid perfusate 1, there was only a slight increase in serum gastric inhibitory polypeptide concentration and insulin secretion increased only slightly. Mean trypsin and bilirubin outputs in the group receiving perfusate 1 were nearly 3 times greater than the outputs of the group receiving the other amino acid mixture. This study expands the importance of intraduodenal amino acid mixtures in stimulating secretion of gastric inhibitory polypeptide and insulin and quantitatively separates gastric inhibitory polypeptide release from release of hormones that stimulate pancreatic enzyme secretion, such as cholecystokinin.
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PMID:Selective release of gastric inhibitory polypeptide by intraduodenal amino acid perfusion in man. 64 19

Casein was modified by use of a series of active N-hydroxy-succinimide esters of amino acids in order to study the effects of new covalently linked hydrophobic or hydrophilic groups on its physical and nutritional properties. Tryptophan was used to determine the best conditions for the chemical reaction and to study the stability of the newly formed amide linkage (isopeptide bond). Casein was also modified with glycine, alanine, methionine, N-acetyl-methionine and aspartic acid. In vitro hydrolysis studies using bovine chymotrypsin, pancreatine and rat bile-pancreatic juice indicated that digestibility of the modified casein derivatives was lower than that of the untreated protein. Since solubility was not significantly changed (except for tryptophyl-casein), the decreased in vitro digestibility is probably due to other factors such as steric hindrance as well as decrease in lysine residues available to trypsin in pancreatin and rat pancreatic juice. Plasma amino acid patterns for rats fed a 10% protein diet of highly modified glycyl-casein or methionyl-casein suggest that the epsilon-aminolysyl derivatives are readily hydrolyzed in vivo. This was confirmed by the growth response of rats fed the following isonitrogenous diets (protein source listed only): casein, casein + free methionine, methionyl-casein, casein + free N-acetyl-methionine, N-acety-methionyl-casein. Covalently attached methionine appeared to be as readily available as the free amino acid; bound N-acetyl-methionine was also available but to a slightly lower extent. Although this study is preliminary, the covalent attachment of amino acids to proteins appears to be a promising method for improving the biological value of food proteins.
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PMID:A method for improving the nutritional value of food proteins: covalent attachment of amino acids. 72 27

The hydrolysis of proteins contained in the dietetic protein-rich bread with crystalline pepsin, trypsin and chemotrypsin was studied for the first time by using an apparatus devised by A. A. Pokrovsky and I. D. Ertanov and by following procedures as proposed by them (1968). By the end of every hour of the experiment 4.31 and 4.04, 7.88 and 4.90, 9.20 and 6.00, 12.96 and 11.72,19.00 and 12.55, 21.14 and 14.00 per cent of the initial quantity of the proteins contained in these two types of bread were hydrolysed respectively. The susceptibility to the action of enzymes on the part of the study products proved much lower than the theoretical proteinic values of the wheat, rye bread (M. S. Marshak, 1971) and below the results obtained by the analogous tests with the proteolysis of the ordinary bread proteins. Inasmuch as the protein-rich bread is baked according to the 1936 formulation an inference is drawn on the expediency of enriching such bread with dairy protein, rye gluten and belip, which will rresult in a more acceptable ratio of tryptophan/lysine and should, apparently, contribute to a greater intensity of the proteins hydrolysis in case of such a bread when it reaches the stomach and the proximal segment of the small intestine.
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PMID:[In vitro susceptibility of the proteins of wheat-protein and bran-protein bread to attack by gastric and pancreatic proteolytic enzymes]. 78 31

A protein proteinase inhibitor was isolated and purified from eggplant exocarp by heat treatment, ammomium sulfate fractionation, column chromatography on DEAE-cellulose, and gel filtration on Sephadex G-25 and G-50. The final purified preparation of the inhibitor was found homogeneous by electrophoretic analysis. The inhibitor showed strong and stoichiometric inhibition on trypsin whereas it showed weak inhibition on alpha-chymotrypsin. It displayed no inhibiting characteristics on pepsin. The molecular weight of the inhibitor was estimated to be approximately 6000. This finding, with the trypsin inhibition data, suggested that the inhibitor combined trypsin in the molar ratio of 1:1. The amino acid analysis indicated that the inhibitor is rich in half-cystine, glycine and aspartic acid, and contains no tryptophan, histidine, methionine or valine.
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PMID:Purification and partial characterization of a protein proteinanse inhibitor isolated from eggplant exocarp. 78 32

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

The amino acid composition of protein was studied with Bacillus megaterium. Most of the essential amino acids are present in sufficient amounts, with the exception of sulphur-containing amino acids and probably tryptophan. The content of methionine is 2 percent. The proteins of the biomass are easily digested by trypsin. The culture of Bac. megaterium grows in a mineral medium containing 5 percent of sucrose or glucose. The yield of dry biomass recalculated for the sugar consumed decreases from 0.6 to 0.3 with an increase of the sugar concentration. The addition of molasses or corn steep increases the yield of the biomass to 15--20 g of dry matter per one litre of the medium. The biomass grown under these conditions contains 8--9 percent of nitrogen, 40 percent of protein, up to 30 percent of poly-beta-hydroxybutyrate in the form of granular inclusions, and 10--14 percent of RNA.
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PMID:[Bacillus megaterium as a possible source of protein]. 80 43

The trypsin inhibitor in eggplant, Solanum melongena L., was isolated and purified by the improved method with the techniques of dialysis using acetylated cellulose tube and ion-exchange chromatography on DEAE-Sephadex. The final preparation was found to be homogeneous by disc and SDS-polyacrylamide gel electrophoresis. This inhibitor had the molecular weight of about 6,200, the pI value of 4.7, and furthermore characteristic amino acid composition lacking in tryptophan, histidine, valine and methionine. The trypsin inhibition data indicated that the purified inhibitor combined with bovine trypsin [EC 3.4.21.4] in the molar ratio of 1:1. These properties of this inhibitor were in agreement with those of the dialyzable eggplant trypsin inhibitor previously purified, indicating that the dialyzable and non-dialyzable inhibitors in eggplant are identical.
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PMID:An improved method for the purification of eggplant trypsin inhibitor. 87 80

An acid stable protease inhibitor was isolated from human bronchial secretion. Two important stages of the purification procedure were affinity chromatography on trypsin bound to Affi-Gel 10 and ion-exchange chromatography on SP-Sephadex C-50. The isolated inhibitor appeared as a single band on analytical disc electrophoresis and eluted as a homogeneous protein peak on gel filtration on Sephadex G-75 corresponding to a molecular weight of about 10500. Amino acid analyses showed no tryptophan or histidine and as N-terminal amino acid tyrosine. No glucosamine or galactosamine was detected. The results of the analyses suggest that the purified inhibitor is identical to the low molecular weight trypsin-chymotrypsin inhibitor of human seminal plasma (HUSI-I).
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PMID:Isolation and partial characterization of a low molecular weight acid stable protease inhibitor from human bronchial secretion. 88 Nov 64


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