title: Effects of estrogen on the turnover rates of ornithine amino transferase in rat liver and kidney.
abstract: The turnover rates of ornithine aminotransferase in the liver and kidney of control rats and those treated with estrogen were determined by injecting L-[14C]leucine (U) and following the decay of specific radioactivity incorporated into immunoprecipitates from the partially purified enzymes. The half-life of the ornithine aminotransferase [EC 2.6.1.13] in the liver (t1/2=0.95 days) was significantly different from that of the kidney enzyme (t1/2=4.0 days). Studies on the incorporation of radioactive leucine into ornithine aminotransferase in the kidney under steady-state conditions showed that the rate of synthesis of this enzyme after treatment with estrogen was 5 to 6 times higher than that in untreated animals. The rate constant of degradation of kidney ornithine aminotransferase under steady-state conditions induced by estrogen treatment was not significantly different from that under control conditions. The results showed that the increase in the rate of biosynthesis, not to a decrease in the rate of degradation. No significant changes in the rates of biosynthesis and degradation of liver ornithine aminotransferase were observed after administration of estrogen.
mesh_terms: D000818:Animals; D004790:Enzyme Induction / Q000187:drug effects; D004967:Estrogens / Q000494:pharmacology*; D006207:Half-Life; D007668:Kidney / Q000187:drug effects / Q000201:enzymology*; D007930:Leucine / Q000378:metabolism; D008099:Liver / Q000187:drug effects / Q000201:enzymology*; D008297:Male; D009928:Organ Specificity; D009953:Ornithine-Oxo-Acid Transaminase / Q000096:biosynthesis / Q000378:metabolism*; D051381:Rats; D000637:Transaminases / Q000378:metabolism*
chemical_list: D004967:Estrogens; D000637:Transaminases; D009953:Ornithine-Oxo-Acid Transaminase; D007930:Leucine