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)

Two forms of ornithine decarboxylase (L-ornithine carboxy-lyase, EC 4.1.1.17) were purified from the livers of rats which had been treated with thioacetamide for 16 h (for details, see miniprint to Obenrader, M.F., and Prouty, W. F. (1977) J. Biol. Chem. 252, 2860-2865). The enzyme was purified over 7,000-fold from liver cytosol with an overall yield of 8%. Enzyme activity was eluted finally in two distinct fractions by chromatography on activated thiol-Sepharose 4B. Both forms appear to be dimeric proteins having molecular weights of approximately 100,000 by equilibrium sedimentation and analysis on a calibrated Sephadex G-200 column. The apparent subunits are approximately 50,000 daltons as determined by electrophoresis on polyacrylamide gels in the presence of sodium dodecyl sulfate. Since electrophoresis in the presence of detergent is the only method used here to indicate subunits, the possibility that conditions of sample preparation resulted in splitting of a labile protein cannot be excluded from consideration. Ornithine decarboxylase has a very broad pH-activity curve with an optimum that shifts from pH 7.0 to pH 7.8 as the enzyme is purified. The apparent Km values for a highly purified mixture of the two forms of enzyme for L-ornithine and pyridoxal 5'-phosphate were determined to be 0.13 mM and 0.25 micronM, respectively. Both sodium and potassium chloride were shown to inhibit enzymatic activity; 50% inhibition occurred at 270 mM for each when Km amounts or ornithine were used. Rat liver ornithine decarboxylase antiserum was prepared in rabbits using Form I of the enzyme as the antigen. The antibody was shown to precipitate quantitatively the ornithine decarboxylase activity isolated from induced rat liver and rat ventral prostate. The specificity of the antiserum was demonstrated by rocket immunoelectrophoresis and by gel electrophoresis in the presence of sodium dodecyl sulfate using immunoprecipitates obtained from enzyme preparations labeled either in vivo, with [3H]leucine, or in vitro, by reductive methylation using formaldehyde and sodium [3H]borohydride. The antibody preparation has been used in a titration method to assess the half-life of antigen in livers of rats induced for ornithine decarboxylase by injection of thioacetamide. In two experiments, the t1/2 of activity at the height of induction, following injection of cycloheximide, was 19 and 24 min, while the t1/2 of disappearance of antigen was 28 and 33 min, respectively. In each experiment the t1/2 for antigen was significantly longer than the t1/2 for loss of enzyme activity. Enzyme levels appear to be modulated primarily by synthesis and degradation of antigen. Furthermore, the observation that enzyme activity is lost with a shorter t1/2 than antigen is consistent with the idea that denaturation is an initial step in the degradation of this enzyme...
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PMID:Production of monospecific antibodies to rat liver ornithine decarboxylase and their use in turnover studies. 1 5

Two different fluorescence cytochemical methods, the formaldehyde-fluorescamine (FF) method and the orthophthalaldehyde (OPT) method as well as an immunocytochemical method have been developed for the localization of spermidine and spermine. Of these three methods, the FF-method is the most easy to perform. We have studied the relationship between fluorescence intensity induced by the FF-method and cellular polyamine levels measured by HPLC in MCF-7 cells and HeLa cells. The experiments were designed to obtain different cell concentrations of polyamines. Cells grown on microscope slides in Petri-dishes were partly depleted of spermidine by two days inhibition of their ornithine decarboxylase activity using alpha-difluoromethylornithine. One hr before harvest the cells were exposed to different concentrations (0-30 microM) of spermidine. Microfluorometric results and chemical determinations of spermidine and spermine were obtained from each separate slide. The cellular total polyamine (spermidine + spermine) concentration on the slides varied between 4 and 15 nmol per mg protein (MCF-7 cells) and 5 and 26 nmol per mg protein (HeLa cells) and the corresponding microfluorometric results between 60 and 115 arbitrary units (MCF-7 cells) and 80 and 160 arbitrary units (HeLa cells). Simple regression analysis showed a good linear relationship between cellular polyamine concentration and FF-fluorescence yield. The correlation coefficient for MCF-7 cells was 0.86 and for HeLa cells 0.82, significance of the correlations was p less than or equal to 0.0001. Our results add further credence to the specificity of the FF-method and indicate that the method may be useful for microfluorometric quantitation of polyamines in situ.
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PMID:Towards microfluorometric quantitation of polyamines in situ. Relationship between cellular polyamine concentration and fluorescence yield of the formaldehyde fluorescamine method. 232 52

The inductions of ornithine decarboxylase (ODC) and DNA synthesis in the pyloric mucosa of the stomach of male F344 rats after oral administrations of chemicals were studied. The glandular stomach carcinogens N-methyl-N'-nitro-N-nitrosoguanidine, N-ethyl-N'-nitro-N-nitrosoguanidine, N-propyl-N'-nitro-N-nitrosoguanidine, 4-nitroquinoline 1-oxide and N-nitroso-N-methylurethane induced up to 100-fold increase in ODC activity in the pyloric mucosa of the stomach; the activity was maximal 24 hr after administration and returned to the control level after 48 to 72 hr. These compounds also induced 14- to 30-fold increase in DNA synthesis in the pyloric mucosa of the stomach; synthesis was maximal 16 to 24 hr after administration and returned to the control level after 144 hr. The non-gastric carcinogens 2-acetylaminofluorene, dimethylnitrosamine and 3-amino-1-methyl-5H-pyrido[4,3-b]indole (Trp-P-2) did not induce ODC or DNA synthesis in the pyloric mucosa of the stomach. Ethyl alcohol also did not induce ODC or DNA synthesis in the pyloric mucosa of the stomach. These results and previous findings that stomach-tumor promoters such as NaCl, taurocholate, glyoxal, K2S2O5 and formaldehyde induced ODC and DNA synthesis in the pyloric mucosa of the stomach of F344 rats suggest that the inductions of ODC and DNA synthesis in the glandular stomach mucosa are markers of promotive activities of complete carcinogens and tumor promoters in the glandular stomach.
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PMID:Inductions of ornithine decarboxylase and DNA synthesis in rat stomach mucosa by glandular stomach carcinogens. 312 39

Administration of formaldehyde at doses of 11 to 110 mg/kg body weight by gastric intubation to male F344 rats induced up to 100-fold increase in ornithine decarboxylase activity with a maximum after 16 hr and up to 49-fold increase in DNA synthesis with a maximum after 16 hr in the pyloric mucosa of the stomach. These results suggest that formaldehyde has tumor-promoting activity in carcinogenesis in the glandular stomach.
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PMID:Inductions of ornithine decarboxylase and DNA synthesis in rat stomach mucosa by formaldehyde. 314 27

Relatively short-term treatment (8 weeks) of rats with N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) in the drinking water (100 mg/l) was shown to adequately initiate gastric carcinogenesis when 10% NaCl was simultaneously administered in the diet. Utilizing this MNNG plus high salt diet as the initiation stage of a two-step protocol, it was also established that subsequent dietary administration of NaCl (10% of the diet) for 32 weeks tended to enhance tumor development in the glandular stomach. Similar tumor promoting activity was demonstrated for other mucosal damaging agents, such as potassium metabisulfite and formaldehyde. Biological changes of the gastric mucosa were examined after chronic administration or a single oral intubation of NaCl. Morphological lesions observed included diffuse mild erosions, atrophy of the glands, and hyperplasia of the foveolar epithelium when given 10% NaCl diet chronically. After a single oral intubation of NaCl, increased tritiated thymidine labeling index and ornithine decarboxylase (ODC) activity were observed in both pyloric and fundic mucosa. No remarkable effects of NaCl were observed on the forestomach or duodenal mucosa. These results suggest that NaCl exerts an enhancing effect at both initiation and promotion steps within the two stage model system of the gastric carcinogenesis, and that these effects of NaCl are possibly related to its mucosal damaging activity.
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PMID:Enhancing effects of dietary salt on both initiation and promotion stages of rat gastric carcinogenesis. 391 94

The effects of several aldehydes and peroxides on growth and differentiation of normal human bronchial epithelial cells were studied. Cells were exposed to formaldehyde, acetaldehyde, benzoyl peroxide (BPO), or hydrogen peroxide (HPO). The effect of each agent on the following parameters was measured: (a) clonal growth rate; (b) squamous differentiation; (c) DNA damage; (d) ornithine decarboxylase activity; (e) nucleic acid synthesis; (f) aryl hydrocarbon hydroxylase activity; and (g) arachidonic acid and choline release. None of the agents were mitogenic, and their effects were assessed at concentrations which reduced growth rate (population doublings per day) to 50% of control. The 50% of control concentrations for the 6-h exposure were found to be 0.065 mM BPO, 0.21 mM formaldehyde, 1.2 mM HPO, and 30 mM acetaldehyde. BPO-exposed cells were smaller than controls (median cell planar area, 620 sq microns versus 1150 sq microns), and acetaldehyde-exposed cells were larger than controls (median cell planar area, 3200 sq microns). All agents increased the formation of cross-linked envelopes and depressed RNA synthesis more than DNA synthesis. HPO caused DNA single-strand breaks, while formaldehyde and BPO caused detectable amounts of both single-strand breaks and DNA-protein cross-links. Other effects included increased arachidonic acid and choline release due to HPO. The similarities and differences of the effects of these aldehydes and peroxides to those caused by tumor promoters are discussed.
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PMID:Effects of formaldehyde, acetaldehyde, benzoyl peroxide, and hydrogen peroxide on cultured normal human bronchial epithelial cells. 398 91