title: [Circadian rhythm of ornithine decarboxylase and its endogenous high molecular weight inhibitor in rat pineal gland].
abstract: The biochemical mechanisms involved in circadian variations of the activity of ornithine decarboxylase (EC 4.1.1.17)--the rate-limiting enzyme of polyamine biosynthesis in rat pineal gland were studied. The enzyme was separated from its endogenous high molecular weight inhibitor by gel-filtration of the cytosol fraction from this organ through Sephadex G-100 in the presence of 250 mM NaCl. The inhibitor was similar in its molecular weight (30 000) and activity to ornithine decarboxylase inhibior from rat liver. The amount of the enzyme in the pineal gland undergoes much smaller circadian variations as compared to that of the inhibitor. It is concluded that the circadian variations of the ornithine decarboxylase activity in the pineal gland may be largely due to the changes in the enzyme/inhibitor ratio.
mesh_terms: D000818:Animals; D002262:Carboxy-Lyases / Q000378:metabolism*; D002940:Circadian Rhythm; D004791:Enzyme Inhibitors / Q000494:pharmacology; D008970:Molecular Weight; D009955:Ornithine Decarboxylase / Q000378:metabolism*; D065108:Ornithine Decarboxylase Inhibitors; D010870:Pineal Gland / Q000201:enzymology* / Q000502:physiology; D011506:Proteins / Q000502:physiology; D051381:Rats
chemical_list: D004791:Enzyme Inhibitors; D065108:Ornithine Decarboxylase Inhibitors; D011506:Proteins; D002262:Carboxy-Lyases; D009955:Ornithine Decarboxylase
vernacular_title: Tsirkadnyĭ ritm aktivnosti ornitindekarboksilazy i ee endogennogo vysokomolekuliarnogo ingibitora v pineal'nom organe krysy.