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:4.1.1.17 (ornithine decarboxylase)
6,351 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Studies were carried out to determine whether the actions of prolactin on the metabolism of the mammary gland may involve polyamines. In mouse mammary gland explants that were preincubated for 2 days with insulin plus hydrocortisone, the rate of [3H]leucine incorporation into casein was enhanced in a prolactin-like manner during a further incubation with spermidine plus cyclic GMP or phospholipase A. Putrescine (0.5 mM) plus PGF2alpha, cyclic GMP or arachidonic acid also enhanced the rate of casein synthesis: but PGF2alpha plus 0.5 mM arginine, ornithine or spermine had no effect. Methyl GAG, an inhibitor of the enzyme S-adenosyl-L-methionine decarboxylase (which is required for the conversion of putrescine to spermidine), abolished the putrescine plus PGF2alpha stimulation of casein synthesis. Since this drug did not affect the action of spermidine plus PGF2alpha on casein synthesis, the specific action of spermidine on casein synthesis is suggested. Neither arginine, ornithine nor the polyamines, by themselves, affected the rate of [3H]uridine incorporation into RNA or the rate of [3H]leucine incorporation into casein. Spermidine levels were elevated within 4 h after adding prolactin to explants which were preincubated for 2 days with insulin plus hydrocortisone; this effect was apparent during incubation periods of up to 48 h with prolactin. Arginase and ornithine decarboxylase activities were also elevated in response to prolactin. Arginase activity was only elevated, however, during long incubation periods with prolactin, i.e., during incubation periods of longer than 2 days. In contrast, ornithine decarboxylase activity was elevated by prolactin within a 30 min incubation period; this effect was maximal after 2 h and persisted during exposure periods of up to 24 h.
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PMID:Regulation of casein synthesis by polyamines in mammary gland explants of mice. 18 30

Isoproterenol (0.3 micronmole/gm body weight) was injected intraperitoneally every 24 h for three days. The synthesis of deoxyribonucleic acid, the concentration of putrescine, spermidine and spermine and the activities of ornithine decarboxylase and S-adenosylmethionine decarboxylase were measured in parotid and submandibular glands at 4 to 8 h after each injection. The parotid glands responded with peaks of DNA synthesis at 24 and 72 h and peaks of putrescine content and decarboxylase activities 8 to 12 h after each injection. Spermidine increased steadily in the parotid, whereas there was little change in the spermine concentration throughout the 72 h. Polyamine metabolism showed much less response in the submandibular gland, and little or no increase in spermidine or spermine levels or in DNA synthesis was observed.
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PMID:Polyamine metabolism in isoproterenol-stimulated mouse salivary glands. 28 8

Elevation of brain GABA levels by GABA-T inhibition is accompanied by a decrease of S-adenosylmethionine decarboxylase activity. This is followed by an increase of ornithine decarboxylase activity and a severalfold increase of brain putrescine levels. Spermidine and spermine levels are not significantly affected under these conditions. These unexpected findings support a regulatory interaction between GABA and polyamine metabolism.
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PMID:Regulatory interrelations between GABA and polyamines. I. Brain GABA levels and polyamine metabolism. 48 78

The distribution of polyamines between the nucleus and the cytoplasm, and the role of the nucleus in polyamine metabolism, have been studied using cells enucleated with cytochalasin B. Spermidine and spermine were found in the nuclear and the cytoplasmic fractions of L929 cells; their concentration was 3-fold higher in the former fraction. Ornithine decarboxylase activity was only found in the cytoplasm, and this activity could be stimulated in enucleated cells by the addition of fresh medium. These cells synthesized putrescine actively, but the putrescine made was not converted to spermidine, and accumulated to relatively high concentrations. Similarly, methionine did not act as a precursor to spermidine in enucleated cells, in contrast to whole cells, although it was incorporated into cell protein. Spermidine synthesis, unlike putrescine synthesis, appears to be completely dependent on a nuclear component.
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PMID:Polyamine metabolism in enucleated mouse L-cells. 56 8

Rat liver undergoes a phase of rapid growth during weaning. We followed the changes in polyamine metabolism occurring during this period of natural growth, and compared them with changes in DNA and RNA accumulation. There was a 2.5-fold increase in the number of cells per liver between suckling (18--19 days old) and weaning (30--32 days old) rats. Ornithine decarboxylase activity increased from the low value in 18-day-old rat pups and remained significantly higher (approx. 5--10-fold) than that in adult rats from day 21 to day 34. Putrescine-dependent S-adenosylmethionine decarboxylase activity was slightly but significantly increased during most of this period. Spermidine and RNA concentrations fluctuated in concert, whereas spermine content per cell doubled during the period from day 23 to day 30.
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PMID:Polyamine metabolism in liver of young rats. 72 81

The enzyme ornithine decarboxylase (L-Ornithine carboxy-lyase, EC 4.1.1.17), has been partially purified from the livers of mice subjected to partial hepatectomy (6-8 h previously). Mouse liver ornithine decarboxylase requires pyridoxal phosphate, and dithiothreitol for maximal activity. The enzyme has a pH optimum of 7.3, it is inhibited in the presence of 0.3 M phosphate, glycine, Tricine and Tris. It shows no dependence on metal ions and is inhibited by high salt concentrations, particularly ammonium salts. The kinetics of the enzyme have been studied with putrescine (and analogs), spermidine and spermine, in the presence of both high and low levels of pyridoxal phosphate. High concentrations of pyridoxal phosphate inhibit the enzyme. The enzyme is also inhibited by low concentrations of putrescine (1 mM). As the concentration of putrescine increased to 10 mM, non-competitive inhibition was observed, this could be reversed by addition of higher levels of pyridoxal phosphate. Spermidine and spermine inhibit (noncompetitively) only at high concentrations (10 mM). Ornithine inhibits at high concentrations (2 mM). Spectral studies have shown that the observed kinetics of competitive inhibition at low concentrations of polyamine changing to noncompetitive inhibition at high polyamine concentrations are due to competition between enzyme and substrate (or inhibitor) for free (non-enzyme bound) pyridoxal phosphate. Noncompetitive inhibition arises through the formation of transient Schiff base complexes between amines and free pyridoxal phosphate. It also appears that the binding of substrate to the active site takes place through Schiff base formation with enzyme bound pyridoxal phosphate.
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PMID:The regulation of mouse liver ornithine decarboxylase by metabolites. 95 46

The effect of methylmercury administration on polyamine synthesis was studied in the liver and kidney of the winter flounder (Pseudopleuronectes americanus). A single injection of methylmercury resulted in five- and sevenfold elevations of ornithine decarboxylase activity in the liver and kidney within 15 and 45 h, respectively. There were elevations of both putrescine- and spermidine-stimulated S-adenosylmethionine decarboxylase activities (approximately 1.5-fold) in both tissues. Evaluation of the polyamine accumulation patterns in these tissues indicated that in the liver all three polyamines increased in concentration until 48 h and then decline. In the kidney, the concentration of putrescine increased steadily until it was 200% of control at 72 h and then declined. Spermidine concentration decreased throughout the time studied and was 17% of control at 1 wk. There was no significant change in the concentration of spermine throughout the period studied. The changes in the polyamine pools and in the activities of the polyamine biosynthetic enzymes after methylmercury administration are consistent with an involvement of the polyamines in the recovery phase to a toxic dose of methylmercury.
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PMID:Polyamine synthesis in liver and kidney of flounder in response to methylmercury. 96 9

The PRO/Re strain of inbred mice are characterized by abnormally high concentrations of proline in both blood (hyperprolinaemia) and urine (prolinuria). They excrete increased amounts of polyamines in their urine. Male PRO/Re mice excreted putrescine at 175% and spermidine at 300% the amount of male C57BL/6J controls. Female PRO/Re mice excreted putrescine at 115% and spermidine at 150% of the amount in the urine of female controls. Examination of the enzymes involved in polyamine biosynthesis revealed that ornithine decarboxylase, the initial enzyme in the polyamine-biosynthetic pathway, was increased by 150% in the kidneys and by 100% in the liver of male PRO/Re mice. There was no significant difference between PRO/Re and C57BL/6J male mice for either putrescine- or spermidine-stimulated S-adenosylmethionine decarboxylase activity. Female PRO/Re mice showed no significant difference from female C57BL/6J mice for any of the enzymes examined. When the concentrations of the polyamines in the tissues of the PRO/Re mice were determined, spermidine and spermine concentrations in the kidneys of the male PRO/Re mice were twice those of the controls. Spermidine concentration in the livers of both male and female PRO/Re mice was approx. 130% that of the controls. Polyamine concentrations in the brains were similar in controls and mutants. The increased polyamine biosynthesis and excretion in the PRO/Re mutant mice may be a mechanism to decrease the extent of proline accumulation.
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PMID:Altered polyamine metabolism in the PRO/Re strain of inbred mice. 98 47

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

Biosynthesis of the polyamines spermidine and spermine and their precursor putrescine is controlled by the activity of the two key enzymes ornithine decarboxylase (ODC) and S-adenosylmethionine decarboxylase (SAMDC). In the adult brain, polyamine synthesis is activated by a variety of physiological and pathological stimuli, resulting most prominently in an increase in ODC activity and putrescine levels. The sharp rise in putrescine levels observed following severe cellular stress is most probably the result of an increase in ODC activity and decrease in SAMDC activity or an activation of the interconversion of spermidine into putrescine via the enzymes spermidine N-acetyltransferase and polyamine oxidase. Spermidine and spermine levels are usually less affected by stress and are reduced in severely injured areas. Changes of polyamine synthesis and metabolism are most pronounced in those pathological conditions that induce cell injury, such as severe metabolic stress, exposure to neurotoxins or seizure. Putrescine levels correlate closely with the density of cell necrosis. Because of the close relationship between the extent of post-stress changes in polyamine metabolism and density of cellular injury, it has been suggested that polyamines play a role in the manifestation of structural defects. Four different mechanisms of polyamine-dependent cell injury are plausible: (1) an overactivation of calcium fluxes and neurotransmitter release in areas with an overshoot in putrescine formation; (2) disturbances of the calcium homeostasis resulting from an impairment of the calcium buffering capacity of mitochondria in regions in which spermine levels are reduced; (3) an overactivation of the NMDA receptor complex caused by a release of polyamines into the extracellular space during ischemia or after ischemia and prolonged recirculation in the tissue surrounding severely damaged areas; (4) an overproduction of hydrogen peroxide resulting from an activation of the interconversion of spermidine into putrescine via the enzymes spermidine N-acetyltransferase and polyamine oxidase. Insofar as a sharp activation of polyamine synthesis is a common response to a variety of physiological and pathological stimuli, studying stress-induced changes in polyamine synthesis and metabolism may help to elucidate the molecular mechanisms involved in the development of cell injury induced by severe stress.
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PMID:Polyamine metabolism in different pathological states of the brain. 135 85


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