Sources of Ammonium in Oat Leaves Treated with Tabtoxin or Methionine Sulfoximine
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چکیده
منابع مشابه
Sources of ammonium in oat leaves treated with tabtoxin or methionine sulfoximine.
Excised 7-day-old oat (Avena sativa L. cv. Jaycee) leaves were incubated in media containing 7.1 millimolar KNO(3) and 0.15 millimolar tabtoxin or 1 millimolar methionine sulfoximine (MSO) to investigate the sources of the observed ammonium accumulated. Tabtoxin and MSO are known inhibitors of glutamine synthetase, the first enzyme in the primary pathway of ammonium assimilation. During a 4- to...
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In developing leaves of Pisum sativum the levels of ammonium did not change during the light-dark photoperiod even though asparaginase (EC 3.5.1.1) did; asparaginase activity in detached leaves doubled during the first 2.5 hours in the light. When these leaves were supplied with 1 millimolar methionine sulfoximine (MSX, an inhibitor of glutamine synthetase, GS, activity) at the beginning of the...
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The N2 fixing bacteria Klebsiella pneumoniae, Azospirillum brasilense, Rhodopseudomonas sphaeroides and Rhodospirillum rubrum, but not Azotobacter vinelandii accumulate the glutamine analogue methionine sulfoximine in the cell. In the accumulating cells methionine sulfoximine inhibits ammonium transport. Accumulation and inhibition are prevented by glutamine.
متن کاملInhibition of glutamine synthetase by methionine sulfoximine. Studies on methionine sulfoximine phosphate.
The irreversible inhibition of glutamine synthetase by methionine sulfoximine is associated with the tight binding to the enzyme of adenosine diphosphate and methionine sulfoximine phosphate; the latter compound can be cleaved nonenzymatically and also by phosphatases to equimolar amounts of methionine sulfoximine and inorganic phosphate. Methionine sulfoximine phosphate is oxidized by L-amino ...
متن کاملEvidence for Ammonium-dependent de Novo Synthesis of Glutamate Dehydrogenase in Detached Oat Leaves.
Glutamate dehydrogenase becomes density labeled through the incorporation of deuterium and (15)N when detached oat leaves (Avena sativa var. Fulghum) are incubated in the presence of ammonia. The enzyme has been isolated by means of DEAE-cellulose chromatography, ammonium sulfate precipitation, isopycnic equilibrium centrifugation, and disc electrophoresis from leaves fed l-methionine-(35)S. Ra...
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ژورنال
عنوان ژورنال: Plant Physiology
سال: 1982
ISSN: 0032-0889,1532-2548
DOI: 10.1104/pp.69.2.345