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)

Two effectors of ornithine decarboxylase (ODC; L-ornithine carboxy-lyase, EC 4.1.1.17) have been extracted from an ODC- (speC-) mutant, Escherichia coli MA 255. One of these is an ODC inhibitor (Mr 15,000 +/- 2000) that is labile to trypsin; its activity increases 20-fold in response to increased polyamine levels in the growth medium. It has additional characteristics similar to those of the ODC antizyme of eukaryote cells: it is a noncompetitive inhibitor of ODC; the complex formed between ODC and the ODC inhibitor can be dissociated with salt to provide active ODC and active ODC inhibitor; furthermore, this E. coli ODC inhibitor is inhibitory to eukaryote ODC. A thermostable nondialyzable factor that activates ODC in vitro has also been extracted from MA255; increased polyamine levels in the growth medium caused a 1.6-fold increase in the activity of this ODC activator. Effectors with comparable activities have also been identified in the parent ODC+ (speC+) strain MA197. The fluctuations of the intracellular levels of these two ODC effectors during the growth of E. coli MA255 have been related to the temporal changes of the activity of ODC in the parent ODC+ MA197 strain. The mode of interaction of these three macromolecules, as reflected in the changes of the activity of ODC, appears to be complex. The results suggest that ODC activity may be controlled post-translationally by macromolecules that act as positive and negative effectors and whose levels fluctuate in response to the concentration of the end products of the reaction.
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PMID:Modulation of ornithine decarboxylase activity in Escherichia coli by positive and negative effectors. 36 95

Putrescine, the end-product of ornithine decarboxylase (ODC: L-ornithine carboxylyase, EC; 4.1.1.17) action, induces the synthesis of a protein(s), in L1210, neuroblastoma, and H-35 cells as well as in rat liver, which inhibits ODC activity. Spermidine and spermine, distal products of ODC activity, also induce the synthesis of a similar protein in H-35 cells. These ODC-inhibitors are heat-labile, trypsin-sensitive, and their induction is dependent upon protein synthesis. They have short half-lives which range from 18 to 66 min; these half-lives are similar to those of the ODC derived from the same source. They are noncompetitive inhibitors of ODC activity with an apparent molecular weight of 26,500. Each inhibitor crossreacts with the ODC's of the other cells and forms an enzyme-inhibitor complex which is stable during Sephadex chromatography; however, after treatment with ammonium sulfate, enzyme and inhibitor activities can be dissociated and recovered intact from the same column. We propose the name antizyme for proteins whose synthesis is induced by the proximal or distal products of the enzyme they inhibit.
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PMID:Induction of a protein inhibitor to ornithine decarboxylase by the end products of its reaction. 106 59

When cultured astroglia are treated with agents that elevate intracellular cyclic AMP, they become process-bearing stellate cells and resemble differentiated astrocytes in vivo. Thrombin rapidly reversed the stellation induced by dibutyryl cyclic AMP, forskolin, or isoproterenol in cultured rat astrocytes; half-maximal and maximal effects occurred at 0.5 and 8 pM, respectively. The proteolytic activity of thrombin was required for stellation reversal, as thrombin derivatized at its catalytic site serine with a diisopropylphospho group was inactive. Two thrombin inhibitors, protease nexin-1 and hirudin, blocked and reversed the effect of thrombin. The stellation reversal effect of thrombin was specific, as 300-1,000-fold higher concentrations of other serine proteinases, including plasmin, urokinase, trypsin, and T cell serine proteinase-1, were ineffective. Thrombin is a mitogen for astrocytes at concentrations in excess of 30 pM. Thrombin increased both cell number and ornithine decarboxylase activity, an early marker for mitogenic stimulation, in astrocyte cultures. The lowest thrombin concentrations that completely reversed astrocyte stellation, however, did not increase ornithine decarboxylase activity. Moreover, several other mitogens for astrocytes did not reverse dibutyryl cyclic AMP-induced stellation. Thus, the stellation reversal effect of thrombin is distinct from the mitogenic response.
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PMID:Reciprocal modulation of astrocyte stellation by thrombin and protease nexin-1. 169 Dec 80

The ornithine decarboxylase-inducing factor (ODC factor) was purified about 1,000-fold in 42% yield from the ascites fluids of an Ehrlich ascites tumor by a combination of centrifugation and concanavalin A (ConA) treatment. A single ip injection of 0.5 micrograms of the purified factor per mouse resulted in half-maximum induction of liver ODC. The factor was found to be a trypsin- and chymotrypsin-resistant, acidic glycoprotein (pI about 4.43) with a minimum molecular weight of about 70 kilodaltons, containing a disulfide bond(s) in its functional domain. It did not react with ConA. This factor induced retrodifferentiation of liver function, causing a marked increase of prototype M2 isozyme of pyruvate kinase. It reduced liver catalase activity, and also modified thyroid hormone metabolism, reducing the serum levels of T4 and T3. These results suggest that the ODC factor is multifunctional and induces many of the changes observed in a tumor-bearing host.
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PMID:Purification of ornithine decarboxylase-inducing factor from cell-free ascites fluid of Ehrlich ascites tumor and its characteristics. 170 56

We examined the role of physiologic plasma concentrations of cholecystokinin (CCK) in the regulation of rat pancreatic gene expression. Postprandial plasma CCK concentrations, as determined by bioassay, were achieved by intraduodenal perfusion with soybean trypsin inhibitor (SBTI) or intravenous infusion of CCK-8. SBTI administration for 48h resulted in nonparallel regulation of digestive enzyme gene expression, as assessed by slot-blot analysis using cloned cDNA probes for trypsin, chymotrypsin, amylase and ribonuclease. As an indicator for pancretic growth stimulation, ornithine decarboxylase (ODC) gene expression was stimulated appr. 2-fold over the SBTI infusion period. Identical effects were seen with i.v. infusion of CCK-8. The CCK receptor antagonist L-364, 718 blocked the effects on pancreatic gene expression of both CCK infusion and SBTI administration. These data therefore indicate that postprandial plasma CCK concentrations regulate pancreatic digestive enzyme and ODC gene expression at a pretranslational level.
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PMID:Cholecystokinin as a regulator of rat pancreatic gene expression. 171 83

One hundred and nineteen isolates of Pseudomonas cepacia, 98 of which were from cystic fibrosis (CF) patients and 21 from environmental and other human sources, were examined for biochemical and exo-enzymatic properties that may contribute to the pathogenicity of this bacterium. The following characteristics were demonstrated significantly more frequently in isolates from CF patients than in control isolates: production of catalase, ornithine decarboxylase, valine aminopeptidase, C14 lipase, alginase and trypsin; reduction of nitrate to nitrite; hydrolysis of urea and xanthine; complete haemolysis on bovine red blood cells; cold-sensitive haemolysis on human red blood cells; greening of horse and rabbit red blood cells. The role of these factors in the pulmonary disease associated with cystic fibrosis is not clear. However, several factors which have been reported previously as being associated with pathogenic processes with other bacteria have now been described in P. cepacia. Additional factors not previously reported as "pathogenicity factors" are also described.
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PMID:Pathogenic factors of Pseudomonas cepacia isolates from patients with cystic fibrosis. 223 77

The primary structure of tyrosine aminotransferase, as deduced from the nucleotide sequence of complementary DNA, was confirmed by fast atom bombardment mass spectrometry of tryptic peptides derived from the purified protein. Limited digestion of the native enzyme with trypsin released an acetylated, amino-terminal peptide; the new amino terminus in the modified enzyme was Val65. Endogenous proteases generated a chromatographically separable form of tyrosine aminotransferase that began at Lys35. Neither trypsin nor the other proteases altered the catalytic activity of tyrosine aminotransferase. Reduction of the holoenzyme with sodium borohydride yielded a major tryptic peptide containing phosphopyridoxamine bound to lysine 280, which probably functions in transamination. The carboxyl terminus of tyrosine aminotransferase contains features that typify proteins with short half-lives; it includes two negatively charged, hydrophilic segments that are enriched for glutamyl residues and are similar to a PEST region in ornithine decarboxylase (Rogers, S., Wells, R., and Rechsteiner, M. (1986) Science 234, 364-368). Tyrosine aminotransferase belongs to a superfamily of enzymes which includes aspartate aminotransferase and can be aligned so that many invariant, functional residues coincide. Like the isoenzymes of aspartate aminotransferase, tyrosine aminotransferase may contain two domains, with a central, catalytic core, and a small domain made up of both amino- and carboxyl-terminal components. We speculate that the exposed small domain may confer the unusually rapid degradative rate that characterizes this enzyme.
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PMID:The structure of tyrosine aminotransferase. Evidence for domains involved in catalysis and enzyme turnover. 256 40

Treatment of PC12 cells with dexamethasone leads, in a period of days, to a 60% decrease in the binding of (125I)nerve growth factor. The decrease was maximal after 3 days of treatment with 1 microM dexamethasone, but some decrease was seen after 6 hr and at concentrations as low as 10 nM. The effect was specific for the glucocorticosteroids. Scatchard plots confirmed the overall loss of nerve growth factor binding, and studies with trypsin digestion and Triton X-100 extraction indicated that the decrease in binding was largely due to a decrease in the number of low-affinity receptors. Nerve growth factor-induced changes, such as the induction of ornithine decarboxylase and the generation of neurites, were inhibited, but only minimally, in dexamethasone-treated cells.
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PMID:Decreased levels of nerve growth factor receptor on dexamethasone-treated PC12 cells. 284 59

The ability of an extract derived from Triticum vulgare, the common wheat plant, to stimulate cellular proliferation of mouse 3T3 fibroblast cells was investigated. Cellular response to Triticum extract (TE) was most evident in sparse cultures made quiescent by growing cells on low concentrations (0.6%) of calf serum. The growth-promoting activity in the extract was lost after dialysis but was resistant to heat treatment and digestion with trypsin or chymotrypsin, suggesting a low-molecular-weight non-protein substance(s). Growth-curve experiments showed that TE was capable of supporting continuous cell division. Cellular proliferation showed a dose-dependent response in the range of 2%-10% TE, and addition of 10% TE to cell culture medium caused a level of cell-growth stimulation approximately 72% that of 20 ng/ml fibroblast growth factor (FGF). Measurement of ornithine decarboxylase (ODC) activity of 3T3 cells after addition of 10% TE showed a significant rise in the specific activity of the enzyme.
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PMID:Stimulation of cell division in mouse fibroblast line 3T3 by an extract derived from Triticum vulgare. 374 20

When monolayer Chinese hamster cells are treated with trypsin for short periods of time, ornithine decarboxylase (ODCase) activity increases two- to fourfold. This increase can be blocked by aprotinin, a protease inhibitor, and is not observed when cultures are dislodged from substrate mechanically prior to contact with exogenous trypsin. The trypsin-induced increase in ornithine decarboxylase activity is not due to degradation of enzyme or inhibitor molecules or to new enzyme synthesis. Immunoprecipitable protein, radiolabeled with [3H]alpha-difluoromethylornithine in vitro, is the same molecular weight in cells harvested with or without trypsin. Protein-bound levels of this specific enzyme-activated irreversible inhibitor of ornithine decarboxylase are unchanged by trypsin treatments that increase enzyme activity. Trypsin treatment of rat embryonic fibroblasts, transformed by a temperature-sensitive mutant of Rous sarcoma virus, increases ODCase activity in cells growing at the nonpermissive, but not at the permissive, temperature for the transformed phenotype. These results suggest that ornithine decarboxylase can be activated by exogenous trypsin treatment in a manner that is dependent on cell adhesion properties, which are modified in transformed cells.
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PMID:Activation of ornithine decarboxylase in monolayer cells treated with trypsin. 384 Aug 6


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