Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:4.1.1.17 (ornithine decarboxylase)
 6,351 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The enzyme spermidine/spermine N1-acetyltransferase (N1-SAT) is rapidly induced by heat shock in CHO and A549 cells, with activity declining by 24 h. Depletion of intracellular polyamines by alpha-difluoromethylornithine, an inhibitor of ornithine decarboxylase, blocks this induction. Re-addition of putrescine to these cultures restores the response to heat shock, with a concomitant increase in intracellular N1-acetylspermidine. Diaminopropane is more than twice as effective as the naturally occurring diamine putrescine, suggesting that the propylamine moiety of spermidine is involved in the regulation of N1-SAT induction. Inhibitor studies indicate transcriptional activation and that the enzyme has an apparent half-life of 30-60 min. A second heat shock rapidly inhibits induced N1-SAT activity, which decays with a half-life of 2-3 min. Despite its induction by heat, N1-SAT is not a stable enzyme, suggesting that the activity observed is not due to a modification of an existing peptide, but is due to a transcriptional event, which may justify the inclusion of this enzyme in the family of heat-shock proteins.
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PMID:Polyamine regulation of heat-shock-induced spermidine N1-acetyltransferase activity. 211 Nov 32

We studied the effects of glucagon and insulin (GI) administration on the inhibition of liver regeneration by acute ethanol treatment after partial hepatectomy (PH) in rats. When ethanol was given 1 hour before PH at 3 gm/kg body wt., [3H] thymidine incorporation into the hepatic DNA 24 hr after PH was significantly inhibited, but it was completely reversed by GI treatment. Although hepatic ornithine decarboxylase (ODC) activity in the ethanol-treated group 4 hr after PH was significantly inhibited, it was completely reversed by GI treatment. The putrescine (PUT) level in the liver 4 hr after PH was decreased by ethanol, but it was increased by GI treatment. At 12 hr after PH, ODC activity was not inhibited and PUT level in the liver was not decreased by ethanol. The levels of spermidine and spermine in the liver 4 hr after PH were unaffected either by ethanol or by GI treatment. Spermidine/spermine-N1 acetyltransferase activity in the liver 4 hr after PH was showed a tendency to increase by ethanol but it was decreased by GI treatment. Difluoromethylornithine, a specific inhibitor of ODC, decreased the level of PUT in the liver, and inhibited [3H] thymidine incorporation. The intraperitotneal administration of PUT significantly increased [3H] thymidine incorporation. The increase in ODC mRNA caused by pH was inhibited by ethanol, but it was completely reversed by GI treatment. SAT mRNA was affected neither by ethanol ner GI treatment. These results suggested that GI treatment was effective on the inhibition of liver regeneration by acute ethanol treatment, and activation of liver regeneration by GI treatment is closely related with ODC induction at the level of transcription.
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PMID:[Effect of glucagon and insulin administration on the inhibition of rat liver regeneration by acute ethanol treatment after partial hepatectomy]. 970 2

The lead enzymes of polyamine biosynthesis, i.e. ornithine decarboxylase (ODC) and arginine decarboxylase (ADC), were not detected in Toxoplasma gondii [the limit of detection for ODC and ADC was 5 pmol min(-1) (mg protein)(-1)], indicating that T. gondii lacks a forward-directed polyamine biosynthetic pathway, and is therefore a polyamine auxotroph. The biochemical results were supported by results obtained from data-mining the T. gondii genome. However, it was possible to demonstrate the presence of a highly active backconversion pathway that formed spermidine from spermine, and putrescine from spermidine, via the combined action of spermidine/spermine N(1)-acetyltransferase (SSAT) or spermidine N(1)-acetyltransferase (SAT) and polyamine oxidase (PAO). With spermine as the substrate, T. gondii SSAT had a specific activity of 1.84 nmol min(-1) (mg protein)(-1), and an apparent K(m) for spermine of 180 mM; with spermidine as the substrate, the SAT had a specific activity of 3.95 nmol min(-1) (mg protein)(-1), and a K(m) for spermidine of 240 mM. T. gondii PAO had a specific activity of 10.6 nmol min(-1) (mg protein)(-1), and a K(m) for acetylspermine of 36 mM. Furthermore, the results demonstrated that T. gondii SSAT was 50 % inhibited by 30 mM di(ethyl)norspermine. The parasite actively transported arginine and ornithine, which were converted via the arginine dihydrolase pathway to citrulline and carbamoyl phosphate, resulting in the formation of ATP via carbamate kinase. The lack of polyamine biosynthesis by T. gondii is contrasted with polyamine metabolism by other apicomplexans.
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PMID:Divergent polyamine metabolism in the Apicomplexa. 1737 21