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)

Cells of the ciliated protozoan Tetrahymena thermophila, grown in proteose peptone medium up to late logarithmic phase, harvested by centrifugation, and resuspended in fresh medium to almost the same cell density, underwent one more division cycle within 5 h after inoculation, thereafter being definitely in full stationary phase. This growth cycle proved to be a useful tool to investigate the activation and deactivation of ornithine decarboxylase ODC1 in Tetrahymena: In late logarithmic phase the cells contained a very low specific activity of ODC of about 3 nmol CO2.h-1.mg-1 in the soluble protein fraction. After growth stimulation the activity was increased up to 100-fold within 1 h. This high activity was maintained for about 5 h-about as long as division activity-then rapidly declined with a half life time (t1/2) of about 15 min to the original low level. Inhibition assays with cycloheximide and actinomycin D revealed that: i. the rapid increase of ODC activity was biphasic with one component of translation of preexisting mRNA and one component of translation of newly transcribed mRNA; ii. the t1/2 of the mRNA of ODC was estimated to be about 2 h; iii. inhibition of protein biosynthesis before ODC inactivation at 5 h caused a decrease of ODC with a t1/2 of 55 min instead of 15 min. These findings suggest that ODC activity in Tetrahymena is regulated on both levels: transcription and translation and by an inactivating protein factor which is regulated at the level of biosynthesis.
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PMID:Regulation of ornithine decarboxylase activity in the growth cycle of Tetrahymena thermophila. 225 30

Basic fibroblast growth factor (bFGF) is a potent mitogen for various cell types. We report here the first study of the effects of bFGF on a digestive tract-derived cell line. The effect of bFGF on the proliferation of AR4-2J cells, tumor cells of acinar pancreatic origin, was investigated together with modulation of ornithine decarboxylase (ODC) activity, an intracellular event involved in cell proliferation. bFGF caused a concentration-dependent stimulation of AR4-2J cell growth, with a half maximal effect (EC50) at 22 +/- 2 pM. ODC activity, assayed by the CO2-trapping method, was also increased by bFGF in a dose-dependent manner, reaching half-maximal stimulation at 20 pM. We conclude that bFGF is a very potent growth promoting factor for cells of pancreatic origin, already effective at picomolar concentrations. The parallelism between the growth assay and the ODC activity assay implicates the involvement of ODC activity in the pathway of the mitogenic effect of bFGF. The stimulation of ODC activity therefore seems to be a reliable early marker for cell proliferation in this model.
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PMID:Regulation of proliferation by fibroblast growth factor in a pancreatic cancer cell line. 226 49

Thapsigargin, a hexaoxygenated tetraacylated sesquiterpene lactone, induced irritation of mouse ear and histidine decarboxylase (HDC) activity in mouse skin, but it did not induce ornithine decarboxylase in mouse skin or adhesion of human promyelocytic leukemia (HL-60) cells. Although thapsigargin did not give consistent positive results in a short-term screening system for tumor promoters, it was tested in a two-stage carcinogenesis experiment on mouse skin. The potency of thapsigargin to induce HDC in mouse skin was used to determine the dose in this experiment. Application of 10 micrograms (17 nmol) thapsigargin induced HDC activity of 139 pmol CO2/mg protein per 60 min. Tumors were found in the skin of 53.5% of the mice treated with DMBA plus 5 micrograms (8.5 nmol) thapsigargin in week 22, in none of those treated with thapsigargin alone by week 30. One tumor appeared in 1 of 15 mice treated with DMBA alone in week 21. Thapsigargin cannot bind to the phorbol ester receptor in the particulate fraction of mouse skin and so is classified as a non-12-O-tetradecanoylphorbol-13-acetate (TPA) type tumor promoter. It is a new tumor promoter differing in many respects from the well-defined TPA type tumor promoters. Several naturally occurring analogues of thapsigargin, such as thapsigargicin and thapsitranstagin, might also be new non-TPA type tumor promoters, because thapsigargicin and thapsitranstagin induced irritation of mouse ear and HDC activity in mouse skin.
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PMID:Thapsigargin, a histamine secretagogue, is a non-12-O-tetradecanoylphorbol-13-acetate (TPA) type tumor promoter in two-stage mouse skin carcinogenesis. 242 75

A sensitive enzyme immunoassay (EIA) was developed for the determination of ornithine decarboxylase (ODC, EC 4.1.1.17), in the range of 0.02-10 ng, using an affinity-purified anti-ODC-Fab'-peroxidase conjugate. The amount of ODC protein was determined in crude extracts from the kidney of testosterone-treated mice, regenerating rat liver and human thyroid carcinoma, with purified mouse kidney or rat liver enzyme as standard. In all these tissues, similar activity/protein ratios were found for ODC: 1.2 x 10(6)-1.9 x 10(6) nmol CO2/h/mg of ODC protein, which were roughly equivalent to the final specific activity of purified enzymes. ODC inactivated by alpha- difluoro-methylornithine (DFMO) could also be assayed with this method similarly to active ODC protein. However, ODC-antizyme complex gave a somewhat lower value than free ODC protein.
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PMID:Sandwich enzyme immunoassay for ornithine decarboxylase. 249 40

A modified microassay for the determination of metabolically generated 14CO2 is described and is applied to the measurement of ornithine decarboxylase in animal tissue preparations. In this technique, the reaction takes place in a microcentrifuge tube inside a 20-ml scintillation vial that also contains a center well with a CO2-trapping agent. The vial is sealed with a silicone septum-lined plastic screw cap. After the initial incubation period during which the enzymatic reaction occurs, acid is injected through the septum into the reaction tube, and 14CO2 is released during a second incubation period. The reaction vial is then removed, counting solution is added to the scintillation vial, and radioactivity is measured. Linearity is present with respect to both increasing amounts of tissue and incubation time. Recovery of evolved 14CO2 was greater (97.5 vs 91.5%) and variation between replicate samples was less (coefficient of variation 2.7 vs 8.5%) when the modified microassay was compared with an assay system that requires removal of the screw cap from the vial before acid injection. The modification allows greater safety and facilitated assays, which could result in savings of both time and laboratory personnel. Special precautions for the use of NaH14CO3 as the recovery marker are noted.
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PMID:Facilitated micromethod for measurement of metabolically generated 14CO2, with application to measurement of ornithine decarboxylase. 249 19

Ornithine decarboxylase (ODC) was induced in rat small intestine by treatment with hypotonic solution in vitro and purified by two procedures, a conventional procedure and an immunoaffinity procedure. SDS-polyacrylamide gel electrophoresis showed that the molecular weight of the preparation purified by the immunoaffinity procedure (Mr = 53,000) was slightly larger than that of the preparation obtained by the conventional procedure (Mr = 52,000). Values for the Km for L-ornithine (0.1 mM), the isoelectric point (5.4), and the final specific activity (5.1-5.5 x 10(5) nmol CO2/mg protein/30 min) of the two preparations were similar to those reported for the rat liver ODC. Addition of a protease inhibitor (limabean trypsin inhibitor) to the crude extract prevented the appearance of the smaller enzyme (Mr = 52,000) obtained by the conventional purification procedure. Our result indicates that the large enzyme is native ODC and the smaller one is a partial proteolysis product of native ODC.
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PMID:Purification and some properties of rat intestinal ornithine decarboxylase. 250 67

The effect of activation of protein kinase C on stimulation of ornithine decarboxylase (ODC) activity and cAMP production was studied in fetal rat osteoblasts. Both phorbol 12-myristate, 13-acetate (PMA), an activator of protein kinase C, and 4 alpha-phorbol, ineffective in activating protein kinase C, failed to stimulate ODC activity and cAMP production. We tested the effect of protein kinase C on stimulation of ODC activity by parathyroid hormone (PTH) and forskolin. In contrast to PTH-stimulated ODC activity, which was not affected by PMA, forskolin-stimulated (1 and 10 microM) ODC activity was dose dependently reduced. PMA (400 nM) reduced both 1 and 10 microM forskolin-stimulated ODC activity to the same level, approximately 3 nmol CO2/mg protein, which suggests a controlling role of protein kinase C in forskolin-stimulated ODC activity. The study of the effect of protein kinase C on PTH- and forskolin-stimulated cAMP production also revealed differences between PTH and forskolin. When PMA was added simultaneously with PTH (4 and 20 nM) or forskolin (1 and 10 microM) the PTH-stimulated cAMP production was dose-dependently potentiated by PMA, whereas forskolin-stimulated cAMP production was not affected. However, both PTH- and forskolin-stimulated cAMP production was dose-dependently augmented when PMA was added 3 min prior to PTH or forskolin. With increasing preincubation periods (up to 24 h) with PMA instead of a potentiation an inhibition was observed. This inhibition is not due to PTH receptor desensitization, although, on basis of the present results desensitization can not completely be excluded. In all cases 4 alpha-phorbol was without effect. The present results show that protein kinase C modulates stimulation of ODC activity and cAMP production in fetal rat osteoblasts. The modulation of both ODC activity and cAMP production appears to be dependent on the nature of the stimulator. The present data suggest a role for protein kinase C in limiting the cAMP-mediated stimulation of ODC activity in these cells. Furthermore, it is suggested that protein kinase C can interfere at more than one site in the cAMP-generating system.
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PMID:Modulatory function of protein kinase C in the activation of ornithine decarboxylase and in cAMP production in rat osteoblasts. 253 85

Ornithine decarboxylase (ornithine carboxy lyase; EC 4.1.1.17) (ODC) from Tetrahymena thermophila was purified 6,300 fold employing fractionated ammonium sulfate precipitation, gel permeation chromatography on Sephadex G-150, ion exchange chromatography on DEAE-Sepharose CL-6B, and preparative isoelectric focussing. The product obtained in 24% yield was a preparation of the specific activity of 10,200 nmol CO2.h-1.mg-1. The purified enzyme was rather stable at 37 degrees C (14% loss of activity within 1 h). The molecular and catalytic properties of this enzyme were investigated. The isoelectric point was 5.7 and the molecular weight (MW) was estimated to be 68,000 under nondenaturing conditions. The pH optimum was between 6.0 and 7.0, the Km for the substrate L-ornithine was 0.11 mM, and the Km for the cofactor pyridoxal 5-phosphate was 0.12 microM; the product of ODC catalysis, putrescine, was a poor inhibitor with an estimated Ki of about 10 mM. The enzyme was inhibited competitively by D-ornithine with a Ki of 1.6 mM and by alpha-difluoromethylornithine with a Ki of 0.15 mM. The latter one, an enzyme activated irreversible inhibitor of mammalian ODC, inactivated the enzyme from T. thermophila at high concentrations with a half life time of 14 min. Other basic amino acids, e.g. L-lysine, L-arginine, and L-histidine, were neither substrates nor inhibitors of the enzyme, as were the diamines 1,3-diaminopropanol and cadaverine, the polyamines spermidine and spermine and the cosubstrate analogues pyridoxal and pyridoxamine-5-phosphate.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Properties of purified L-ornithine decarboxylase (EC 4.1.1.17) from Tetrahymena thermophila. 260 Aug 81

Spermidine was detected as the major polyamine of Ancylostoma ceylanicum as well as Nippostrongylus brasiliensis. Spermine was present in lower amounts whereas the level of putrescine was even less. S-Adenosylmethionine decarboxylase, a rate-limiting enzyme in the biosynthetic pathway of polyamines, was demonstrated at low levels in both parasites. Decarboxylation of lysine and arginine was absent or negligible and that of ornithine questionable, as the enzyme activity was not inhibited by alpha-difluoromethylornithine while RMI 71,645, an irreversible inhibitor of ornithine aminotransferase, strongly inhibited the liberation of CO2 from ornithine. High activity of ornithine aminotransferase was observed in both the parasites and may interfere with the assay for ornithine decarboxylase. Adults of A. ceylanicum were found to rapidly take up spermidine and spermine from incubation medium while uptake of putrescine was very low. These results indicate that hookworms depend on uptake and interconversion rather than de novo synthesis for their polyamine requirement.
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PMID:Polyamine metabolism in Ancylostoma ceylanicum and Nippostrongylus brasiliensis. 272 92

Studies on the decarboxylation of ornithine in Leishmania mexicana have shown that this activity corresponds to a true ornithine decarboxylase rather than to an oxidative decarboxylation or aminotransferase reaction, both of which also give rise to the release of CO2. The stoichiometric relationship between substrate and products has indicated that extracts of L. mexicana were able to catalyse the formation of an unknown compound besides putrescine and CO2. The addition of cycloheximide to cultures of L. mexicana allowed us to demonstrate that ornithine decarboxylase degradation in vivo was extremely slow in this parasite. This remarkable stability of the enzyme is only comparable to that found in Trypanosoma brucei and contrasts with the high turnover rate of ornithine decarboxylases of different mammalian cells.
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PMID:Stable ornithine decarboxylase in promastigotes of Leishmania mexicana mexicana. 273 21


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