[Characteristics of NADP-dependent isocitrate dehydrogenase functioning in pea leaves during salt stress].
In pea seedlings transferred to a medium containing 3% NaCl, NADP-dependent isocitrate dehydrogenase (NADP-IDH) activity in leaves increased more than twofold during the first hour, decreased, and increased again (approximately 1.5 times) by the 14th hour of exposure. Some catalytic and regulatory properties of NADP-IDH were studied using enzyme preparations purified from normal plants and plants exposed to salt stress. The results showed that Km for NADP-IDH in reactions with isocitrate and NADP decreased under stress by factors of 2 and 3, respectively. Specific features of enzyme activity regulation by citrate and trans-aconitate under these conditions were revealed. The inhibitory effects of gamma-aminobutyric acid (GABA) and 2-oxoglutarate on NADP-IDH from plants exposed to salt stress was stronger than that on the enzyme from normal plants. Glutamine and glutamate slightly activated the enzyme in both cases.
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Timiryazev Institute of Plant Physiology, Russian Academy of Sciences, Botanicheskaya ul. 35, Moscow, 127276 Russia.
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Izmaĭlov
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D000156:Aconitic Acid / Q000494:pharmacology; D002384:Catalysis; D003470:Culture Media; D004791:Enzyme Inhibitors / Q000494:pharmacology; D018698:Glutamic Acid / Q000494:pharmacology; D005973:Glutamine / Q000494:pharmacology; D007521:Isocitrate Dehydrogenase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D007656:Ketoglutaric Acids / Q000494:pharmacology; D007700:Kinetics; D009997:Osmotic Pressure; D018532:Pisum sativum / Q000201:enzymology*; D018515:Plant Leaves / Q000201:enzymology*; D012965:Sodium Chloride / Q000378:metabolism*; D005680:gamma-Aminobutyric Acid / Q000494:pharmacology
D003470:Culture Media; D004791:Enzyme Inhibitors; D007656:Ketoglutaric Acids; D005973:Glutamine; D018698:Glutamic Acid; D012965:Sodium Chloride; D005680:gamma-Aminobutyric Acid; D000156:Aconitic Acid; D007521:Isocitrate Dehydrogenase; C039355:isocitrate dehydrogenase (NADP+)