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)

New inhibitor or inhibitors of nicotinamide-adenine dinucleotide-dependent 15-hydroxyprostaglandin dehydrogenase (PGDH) activity were found in breast milk but not in powdered milk. Milk samples were obtained manually from 23 puerperae who had delivered at 38 to 41 weeks. The inhibition pattern was competitive and noncompetitive. The percentage of inhibition of PGDH activity kept at 4.0 degrees C increased to a maximum at 12 hours after milk sampling and decreased thereafter. The percentage of inhibition of each milk sample decreased gradually with the duration postpartum. In addition, the inhibitor or inhibitors showed a smaller molecular weight than 1000 daltons and were partially resistant to heat and trypsin. Moreover, they were easily soluble in petroleum ether at various pH values, although the adsorption to C18 cartridge was inadequate. These new factor or factors may increase the benefits of breast feeding.
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PMID:New inhibitor(s) of 15-hydroxyprostaglandin dehydrogenase in human milk. 334 68

Information about the location of the active site of diphtheria toxin was derived from proteolysis studies and an analysis of its sequence. It was found that a specific trypsin cleavage within whole diphtheria toxin occurs at Lys-39. Therefore, Lys-39 appears to be a surface residue. Furthermore, protection from proteolysis could be obtained upon binding of either the substrate beta-nicotinamide adenine dinucleotide (oxidized form) (NAD+) or a competing ligand, adenylyl(3'-5')uridine 3'-phosphate (ApUp). The protection by ApUp, which binds to the toxin very tightly, required only stoichiometric levels. The most likely explanation of these results is that both NAD+ binding and ApUp binding block trypsin either through a steric mechanism or through a local conformational change, suggesting Lys-39 may be near the active site. Further evidence supporting this conclusion comes from comparison of the previously determined sequences of diphtheria toxin and of Pseudomonas exotoxin A, a protein that catalyzes an identical reaction. We find a significant degree of homology between the N-terminal halves of the catalytic domains of these two proteins, which apparently represents active-site residues, and that Lys-39 is in the center of the homologous sequence. Furthermore, the location of the amino acid that is the homologue of Lys-39 within the crystal structure of Pseudomonas exotoxin A is also in agreement with a location in or near the active site. Other unusual features in the sequences of diphtheria toxin and Pseudomonas exotoxin A are also described, and on the basis of the experiments presented, a possible function for ApUp is considered.
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PMID:Localization of the active site of diphtheria toxin. 339 Apr 39

In vitro formation of reduced nicotinamide adenine dinucleotide phosphate (NADPH)-nitrate reductase (NADPH: nitrate oxido-reductase, EC 1.6.6.2) has been attained by using extracts of the nitrate reductase mutant of Neurospora crassa, nit-1, and extracts of either photosynthetically or heterotrophically grown Rhodospirillum rubrum, which contribute the constitutive component. The in vitro formation of NADPH-nitrate reductase is characterized by the conversion of the flavin adenine dinucleotide (FAD) stimulated NADPH-cytochrome c reductase, contributed by the N. crassa nit-1 extract from a slower sedimenting form (4.5S) to a faster sedimenting form (7.8S). The 7.8S NADPH-cytochrome c reductase peak coincides in sucrose density gradient profiles with the NADPH-nitrate reductase, FADH(2)-nitrate reductase and reduced methyl viologen (MVH)-nitrate reductase activities which are also formed in vitro. The constitutive component from R. rubrum is soluble (both in heterotrophically and photosynthetically grown cells), is stimulated by the addition of 10(-4) M Na(2)MoO(4) and 10(-2) M NaNO(3) to cell-free preparations, and has variable activity over the pH range from 3.0 to 9.5. The activity of the constitutive component in some extracts showed a threefold stimulation when the pH was lowered from 6.5 to 4.0. The constitutive activity appears to be associated with a large molecular weight component which sediments as a single peak in sucrose density gradients. However, the constitutive component from R. rubrum is dialyzable and is insensitive to trypsin and protease. These results demonstrate that R. rubrum contains the constitutive component and suggests that it is a low molecular weight, trypsin- and protease-insensitive factor which participates in the in vitro formation of NADPH nitrate reductase.
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PMID:In vitro formation of nitrate reductase using extracts of the nitrate reductase mutant of Neurospora crassa, nit-1, and Rhodospirillum rubrum. 427 Apr 47

Electrohydraulic shock was shown to produce oxidation reactions which inactivated certain compounds important in cellular metabolism. Enzymes that were inactivated included lactic dehydrogenase, trypsin, and proteinases of Bacillus subtilis. Free sulfhydryl groups and reduced nicotinamide adenine dinucleotide were oxidized. Adenosine triphosphate was destroyed, but deoxyribonucleic acid was not affected. Intracellular material of Escherichia coli lost its ability to absorb at 260 mmu after electrohydraulic shock. The bactericidal mechanism involved appeared to be due to nonselective oxidation reactions produced by high-voltage discharges in water. These oxidation reactions were probably mediated by free radicals produced in the water.
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PMID:Mechanism of the bactericidal action produced by electrohydraulic shock. 429 20

Allen, Emma G. (Downstate Medical School, State University of New York, Brooklyn). Use of tetrazolium salts for electron transport studies in meningopneumonitis. II. Reduced nicotinamide adenine dinucleotide phosphate system. J. Bacteriol. 92:1041-1046. 1966.-The conditions of electron transfer from nicotinamide adenine dinucleotide phosphate in meningopneumonitis (MP) are described and compared with electron transfer from nicotinamide adenine dinucleotide by this organism. The observations suggest that, in either system, there may be more than one pathway of electron flow, and that these pathways differ from those in normal membrane particulates. It was also found that after trypsin treatment, particulates from pools of normal allantoic fluids and membranes retain the normal characteristics, whereas those from pools of MP-infected fluids and membranes assume the characteristics of MP particles from fluids.
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PMID:Use of tetrazolium salts for electron transport studies in meningopneumonitis. II. Reduced nicotinamide adenine dinucleotide phosphate system. 438 Aug 66

In vitro complementation of the soluble assimilatory nicotinamide adenine dinucleotide phosphate, reduced form (NADPH)-nitrate reductase was attained by mixing cell-free preparations of certain Neurospora nitrate reductase mutants: induced nit-1 (uniquely possessing inducible NADPH-cytochrome c reductase) with (a) uninduced or induced nit-2 or nit-3, or (b) uninduced wild type. The complementing activity of induced nit-1 is soluble while that of nit-2, nit-3, and wild type is particulate but not of mitochondrial origin. All fractions are inactivated by heat or trypsin. The NADPH-nitrate reductase enzymes formed in the above three complementing mixtures are similar to the wild-type enzyme in sucrose density gradient profiles, molecular weight, substrate affinity, sensitivity to inhibitors and temperature, but show different ratios of associated enzyme activities. The data suggest that nitrate reductase consists of at least two protein subunits: a nitrate-inductible subunit as reflected by inductible NADPH-cytochrome c reductase, and a constitutive protein which is activated (as indicated by the appearance of flavine adenine dinucleotide, reduced form (FADH(2))- and reduced methyl viologen-nitrate reductase activities) when it combines with the inductible subunit.
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PMID:Formation of assimilatory nitrate reductase by in vitro inter-cistronic complementation in Neurospora crassa. 439 54

We studied the effect of rat tissue extracts on induction of lambda prophage in Escherichia coli (lambda) by L-azaserine. Hepatic and pancreatic extracts, primarily the cytosolic fraction, markedly increased the rate of induction. Hepatic extracts from lipotrope-deficient rats were somewhat more active than extracts from normal rats. The enhancing activity in normal rat hepatic cytosol was partially characterized. It reduced by about one-half the dose of azaserine required for a given purpose. The enhancement was increased by preincubating the bacterial cells with cytosol; cells retained the effect after cytosol was removed. Enhancing activity was inhibited strongly by the amino acids phenylalanine, tryptophan, and tyrosine; to lesser extents by leucine, methionine, and serine; and not at all by proline or glutamine. It was eliminated by dialysis of the cytosol and reduced by omission of nicotinamide adenine dinucleotide phosphate (NADP) from the reaction mixture. Heating the cytosol to 60 degrees C or 80 degrees C or varying the pH of the reaction mixture from 6 to 8 had no significant effect. Treating the cytosol with trypsin appeared to release an inhibitor of the activity. Glutathione, cysteine, and beta-mercaptoethanol also enhanced lambda induction by azaserine, but the cytosolic activity was not affected by the thiol-inactivating compound diethylmaleate (DEM). The results suggest that factors in cytosol interact with bacterial cells to facilitate transport of azaserine into the cells, primarily through the aromatic amino acid transport system. A small molecule, not a free thiol compound, appears to be involved. It may serve to establish reducing conditions protective for azaserine, the probable mechanism of action of sulfhydryl compounds.
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PMID:Enhancing activity of rat tissue extracts for induction of lambda prophage by L-azaserine. 623 74

The alpha-oxidation of [1-14C]phytanic acid of high specific activity was studied in postnuclear and various subcellular fractions from rat liver. alpha-Oxidation in the postnuclear fraction required ATP, Mg2+, nicotinamide, and molecular oxygen for activity. alpha-Oxidation was inhibited by iron-specific chelating agents and respiratory chain inhibitors. Partial inhibition by carbon monoxide indicated a possible involvement of cytochrome P-450. However, phenobarbital-treated rat liver postnuclear fraction did not stimulate phytanic acid alpha-oxidation above that of control. Subcellular fractionation indicated that in addition to the mitochondrial fraction, cytosol was required for activity. The cytosolic factor appeared to be dialyzable; it was inactivated by heat treatment, but not affected by trypsin digestion. NAD, CoA, ascorbic acid, and catalase did not replace cytosolic activity nor did the recently characterized heat-stable factors in brain hydroxylation, namely, adenosine nucleotides and glutamate.
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PMID:Phytanic acid alpha-oxidation in rat liver. Requirement of cytosolic factor. 623 33

Branched-chain alpha-ketoacid dehydrogenase has been purified to homogeneity from bovine liver mitochondria. The isolated complex has a specific activity of 5-8 mumol of reduced nicotinamide adenine dinucleotide min-1 (mg of protein)-1 as isolated and does not require the addition of exogenous lipoamide dehydrogenase for activity. Addition of porcine heart lipoamide dehydrogenase stimulated complex activity by no more than 20%. Four subunits copurify with the complex with molecular weights by sodium dodecyl sulfate-polyacrylamide gel electrophoresis of 55 000, 52 000, 46 500, and 37 500. Here we show that the 52 000-dalton subunit is the lipoyl-containing transacylase component of the complex. Data are presented to support the hypothesis that the branched-chain ketoacid dehydrogenase complex is physically and catalytically similar to, but separate from, the pyruvate and alpha-ketoglutarate dehydrogenase complexes. The transacylase of the branched-chain ketoacid dehydrogenase complex has an exposed trypsin-sensitive region. Proteolytic action of trypsin separates a lipoyl-containing component from the remainder of the protein. Data from our laboratory presented here and elsewhere define a specific function for three of the four subunits.
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PMID:Identification of specific subunits of highly purified bovine liver branched-chain ketoacid dehydrogenase. 665 74

1. Staphylococcal enterotoxin A (SEA) was exposed in a state of limited proteolysis to five kinds of proteolytic enzymes: papain, pepsin, pronase, trypsin and alpha-chymotrypsin. SEA was found to be sensitive to the action of three of them: papain, pepsin and pronase. 2. Four fragments were produced after papain proteolysis of SEA in the presence of beta-mercaptoethanol. 3. Papain processing of SEA does not influence its capacity to interact with antibodies to intact toxin, but the capacity of SEA to hydrolyse NAD to nicotinamide (NA) and adenosinediphosphatribose (ADP-ribose) completely disappears. 4. SEA under the action of pepsin and pronase has been hydrolysed to small peptides, which appear to be moving with the front of leading dye in disc-electrophoresis.
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PMID:Properties of staphylococcal enterotoxin A under limited proteolysis. 704 84


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