The Change in Arginine Levels and the Metabolism of Urea and Ornithine in <i>Cucurbita moschata</i> Seedlings

Lignowski, E. M.; Splittstoesser, Walter E.

doi:10.1111/j.1399-3054.1971.tb01432.x

Cited by 23 publications

(10 citation statements)

References 15 publications

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“…The use of [U-14C]arginine as the substrate for ADC assay raises the possibility that a part of ~4CO2 released may be contributed by ODC activity as a consequence of conversion of a portion of the labelled substrate to 14C-ornithine through arginase-type of activity since arginase-urease type of activity has been demonstrated in Cucurbita seedlings (Lignowski and Splittstoesser 1971) and ODC activity is shown to be modulated during growth in some specialized plant tissues (Altman et al 1983). However, it has been unequivocally established earlier (Suresh et al 1978) that under the standard assay conditions employed here for ADC quantification, 14CO2 liberated with [U-14C]arginine as the substrate reflects true ADC activity and is uninfluenced by arginase-urease type of reaction.…”

Section: Discussionmentioning

confidence: 97%

Modulation of arginine decarboxylase activity in cucumber (Cucumis sativus) cotyledons in short-term organ culture

Prasad

Adiga

1985

J Plant Growth Regul

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Abstract. Among the various amines administered to excised Cucumis sa-tivus cotyledons in short-term organ culture, agmatine (AGM) inhibited arginine decarboxylase (ADC) activity to around 50%, and putrescine was the most potent entity in this regard. Homoarginine (HARG) dramatically stimulated (3-to 4-fold) the enzyme activity. Both AGM inhibition and HARG stimulation of ADC were transient, the maximum response being elicited at 12 h of culture. Mixing experiments ruled out involvement of a macromolecular effector in the observed modulation of ADC. HARG-stimulated ADC activity was completely abolished by cycloheximide, whereas AGM-mediated inhibition was unaffected. Half-life of the enzyme did not alter on treatment with either HARG or AGM. The observed alterations in ADC activity are accompanied by change in K m of the enzyme. HARGstimulated ADC activity is additive to that induced by benzyladenine (BA) whereas in presence of KC1, HARG failed to enhance ADC activity, thus demonstrating the overriding influence of K + on amine metabolism.

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Section: Discussionmentioning

confidence: 97%

Modulation of arginine decarboxylase activity in cucumber (Cucumis sativus) cotyledons in short-term organ culture

Prasad

Adiga

1985

J Plant Growth Regul

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“…This sequence of reactions was observed in extracts from Cucurbita seedlings (13). However, no urease activity could be detected in the partially purified preparations from avocado4fruits eliminating possible '4CC2 release other than through ADC activity.…”

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confidence: 88%

Partial Purification and Characterization of Arginine Decarboxylase from Avocado Fruit, A Thermostable Enzyme

Winer¹,

Vinkler²,

Apelbaum³

1984

Plant Physiol.

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ABSTRACrA partially purified preparation of arginine decarboxylase (EC 4.1.1.19), a key enzyme in polyamine metabolism in plants, was isolated from avocado (Persea americana Mill. cv Fuerte) fruit. The preparation obtained trom the crude extract after ammonium sulfate precipitation, dialysis, and heat treatment, had maximal activity between pH 8.0 and 9.0 at 60°C, in the presence of 1.2 millimolar MnCl2, 2 millimolar dithiothreitol, and 0.06 millimolar pyridoxal phosphate. The Km of arginine for the decarboxylation reaction was determined for enzymes prepared from the seed coat of both 4-week-old avocado fruitlet and fuHly developed fruit, and was found to have a value of 1.85 and 2.84 millimolar, respectively. The value of Pl,P,,., of these enzymes was 1613 and 68 nanomoles of C02 produced per milligram of protein per hour for the fruitlet and the fully developed fruit, respectively. Spermine, an end product of polyamine metabolism, caused less than 5% inhibition of the enzyme from fully developed fruit and 65% inhibition of the enzyme from the seed coat of 4-week-old fruitlets at I millimolar under similar conditions. The effect ofdifferent inhibitors on the enzyme and the change in the nature of the enzyme during fruit development are discussed.It is well established that the intracellular concentration of polyamines changes markedly in response to conditions which affect growth and development of plant tissue (1 1, 12). Hence, processes like cell division (7) or cell differentiation (4, 9) are deemed to be regulated by polyamines. The properties of the enzymes involved in the biosynthesis of polyamines and their degradation, and the mode by which the activities of these enzymes are regulated, may therefore contribute to our understanding of the overall processes of development and senescence of fruits.Whereas in mammalian cells putrescine is synthesized from Lornithine by ornithine decarboxylase (22), there have been a number of reports indicating that putrescine in plants is formed from L-arginine (19). Arginine is converted by ADC2 to agmatine which is then converted to putrescine (1,11,12). In recent studies by Heimer et al. (10) and Cohen et al. (6) on tomato ovaries and fruits, it was observed that the activity of ODC changed during fruit development, whereas the relatively low '

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“…The germination stage of many plant seeds usually has a significant increase of glutamine content in the cotyledons and developmental pattern appears to be closely related to that of glutamine synthetase activities. The maximum activity of glutamine synthetase is observed at the peak period of axis growth and the transport of nitrogen to axis from cotyledons of etiolated seedlings (12). It is most likely that the glutamine synthetase activity involved in this metabolic event is associated with the cytosolic fraction.…”

mentioning

confidence: 99%

“…It is known that in green plants glutamine serves in the cotyledons of pumpkin seedling is transported to the embryonic axis in the form of glutamine (12). Inasmuch as a large increase of glutamine content in the cotyledons during germination has been observed, it is conceivable that glutamine synthetase plays an important role of synthesizing glutamine from the storage proteins.…”

mentioning

confidence: 99%

“…During germination of pumpkin seedling, hydrolysis of storage proteins produces free amino acids, which could be metabolized in the cotyledons or transported directly to the growing embryonic axis. Lignowski et aL (12) have shown that during the first 8 d of pumpkin germination, 75% of the storage protein hydrolyzed and 50% of the total nitrogen in the cotyledons is transported to the axis tissue in the form of glutamine. The germination stage of many plant seeds usually has a significant increase of glutamine content in the cotyledons and developmental pattern appears to be closely related to that of glutamine synthetase activities.…”

mentioning

confidence: 99%

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Developmental Formation of Glutamine Synthetase in Greening Pumpkin Cotyledons and Its Subcellular Localization

Nishimura

Bhusawang²,

Strzałka³

et al. 1982

Plant Physiol.

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During the germination of pumpkin (Cucurbita sp. Amakuri Nankin) seeds in dark, the activity of glutamine synthetase in cotyledons gradually increased, reaching a maximum at 5 to 6 days. A measurable enhancement (about 4-fold) of the enzyme activity occurred when the seedlings were exposed to continuous illumination from day 4 up to day 8. Glutamine synthetase activity was detectable only in the cytosolic fraction in the etiolated cotyledons, whereas it was found both in the cytosolic and chloroplast fractions in the green cotyledons. The two isoenzymes of glutamine synthetase have been separated by DEAE-ceilulose column chromatography of extracts from the green cotyledons. These data indicate that during the greening process the chloroplastic glutamine synthetase is newly synthesized. The roles of cytosolic and chloroplastic glutamine synthetase in germinating pumpkin cotyledons concerning assimilation of NH3 are discussed.

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The Change in Arginine Levels and the Metabolism of Urea and Ornithine in Cucurbita moschata Seedlings

Cited by 23 publications

References 15 publications

Modulation of arginine decarboxylase activity in cucumber (Cucumis sativus) cotyledons in short-term organ culture

Modulation of arginine decarboxylase activity in cucumber (Cucumis sativus) cotyledons in short-term organ culture

Partial Purification and Characterization of Arginine Decarboxylase from Avocado Fruit, A Thermostable Enzyme

Developmental Formation of Glutamine Synthetase in Greening Pumpkin Cotyledons and Its Subcellular Localization

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