The Biosynthesis of Amino Acids

Mattoon, James R.

doi:10.1016/b978-0-08-002925-2.50007-3

Cited by 5 publications

(3 citation statements)

References 298 publications

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“…These amino acid analyses indicated that a distinct regula- 4 After low temperature treatment of C. tory process exists in the synthesis of arginine and glutamine in the tree. The synthesis and accumulation of glutamine (and glutamate) are predominant during the growth phase, while during the wintering phase arginine is a major storage amino acid, particularly in the xylem.…”

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confidence: 99%

Effect of Low Temperature on Amino Acid Metabolism in Wintering Poplar

Sagisaka

1974

Plant Physiol.

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Analyses of free amino acids in poplar (Populus geirica) were carried out throughout a year to see the effect of low temperature on a system regulating amino acid metabolism in the tree. The results indicated that during the wintering phase arginine was the major amino acid both in bark and xylem, particularly in xylem, and that at the time of budding and growing glutamine and glutamate became dominant. Changes in the relative levels of glutamine (plus glutamate) and arginine to the total amino acids of the a-ketoglutarate family indicated the presence of a regulatory system annually controlling the synthesis between glutamine (plus glutamate) and arginine. The system appeared to be governed and sensitized by low temperatures. Neither a transition of the synthesis from arginine to glutamine (plus glutamate) nor budding occurred in the poplars which spent the winter months in a greenhouse.Glutamate and glutamine play a major role in amino acid biosynthesis from ammonia as well as from other nitrogenous materials in higher plants (1, 2). Actually, in perennials such as poplar (Populus gelrica) a large amount of glutamine is accumulated both in the living bark and xylem at the time when trees are growing (6).The previous report has shown that prior to the period of accumulation of glutamine, arginine accumulated in the wintering poplar (6). With the arrival of spring, a striking decrease in the arginine level was observed, particularly in the xylem, concomitant with an increase of glutamine and glutamate.In spite of the general acceptance of the importance of exposing dormant perennials to low temperatures to evoke a renewal of active growth (3, 5), little information is available on the transition of amino acid metabolism occurring in the twig of the tree. In an attempt to clarify the biochemical effect of low temperatures on the metabolic activities of wintering plants, the relation between low temperatures and amino acid metabolism in the poplar tree was studied. This paper indicates that the decrease of the accumulated arginine and the increase of glutamine (and glutamate) is coupled with the budding process and that the regulatory system appears to be sensitized by low temperatures.A 5-year-old poplar was grown in the field, and comparable samples of twigs were taken from the tree. For free amino acid analysis, twigs were sampled regularly on the 20th of each month throughout 1 year, and extracts for the analysis were prepared immediately as described previously (6).The results are shown in Tables I and II. Glutamine and glutamate constituted the major fraction of amino acids of the a-ketoglutarate family (glutamine, glutamate, proline, and arginine) (1, 4) during the period of active growth, while arginine was the major amino acid of the family during winter. From the data in Tables I and II, the percentage of arginine (and glutamine plus glutamate) relative to the total of the a-ketoglutarate family of amino acids was obtained (Fig.

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confidence: 99%

Effect of Low Temperature on Amino Acid Metabolism in Wintering Poplar

Sagisaka

1974

Plant Physiol.

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“…Rather it is glutamate that most likely plays a pivotal role as an intermediate in the biosynthesis of kainic acid and domoic acids, as it does in proline biosynthesis (Mattoon, 1967). Condensation of a suitably activated glutamate precursor with either a C 5 or a CIO isoprenoid pyrophosphate unit could generate kainic or domoic acid respectively (Fig.…”

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confidence: 99%

Glutamate agonists from marine algae

Laycock¹,

Freitas²,

Wright³

1989

J Appl Phycol

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The occurrence of three glutamate agonists -glutamic acid, D-homocysteic acid and kainic acid -in a spontaneous mutant of Palmaria palmata is reported. Glutamic acid and D-homocysteic acid, but not kainic acid, were found in the wild-type plant. The closely related glutamate agonist, domoic acid, was found in the red alga Chondria baileyana and in the diatom Nitzschia pungens forma multiseries. In the diatom, domoic acid can build up to high levels in excess of 3 % (dry wt.), making N. pungens a potential commercial source of this neuroactive amino acid. Information is also presented on the distribution, chemistry and biological activity of neuroactive amino acids from algae, and a possible biogenic relationship among kainoid metabolites is discussed.

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“…Aspartokinase catalyses the phosphorylation of aspartate to aspartylphosphate, the first intermediate in the branched pathway for the synthesis of lysine, methionine, threonine and isoleucine (Mattoon, 1967 intermediates and end-products of this pathway has been well established as a major regulatory process in many bacteria (Datta & Gest, 1964;Tristram, 1968;Cohen, Stanier & Le Bras, 1969). As Mattoon (1967) pointed out, such inhibition could result in interference with the synthesis of the other end-products of the pathway, thus leading to an imbalance in amino acid biosynthesis. In coliform bacteria, however, this does not occur as multiple aspartokinases are present, each subject to control by different end-products (Stadtman et al 1961;Cohen et al 1969).…”

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Inhibition by L-Threonine of Aspartokinase as a Cause of Threonine Toxicity to Methylococcus capsulatus

Eccleston¹,

Kelly²

1973

Journal of General Microbiology

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We have previously suggested that the inhibition of growth of Methylococcus capsirlatiis by L-threonine resulted from interference with early steps in the branched pathway for the biosynthesis of the aspartate-family amino acids (Eccleston & Kelly, I 972 a). We now present evidence to suggest that aspartokinase may be the enzyme critically affected by L-threonine.Wild-type and threonine-resistant strains of Methylococcus capsulatus were cultured in (1955). Reactions were terminated by adding the acid-ferric reagent and mixtures blended by vigorous mechanical agitation. Absorbance at 540 nm was measured in a Unicam SP 600 Series I1 spectrophotometer against zero-time blanks. Values obtained were corrected for colour developed in controls from which aspartate was omitted. Standards were prepared using DL-aspartic acid P-hydroxamate monohydrate (Sigma Chemical Co., London) and enzyme activities calculated as nanomoles of asparthydroxamate formed/mg protein/min. Activity was proportional to extract concentration up to about I mg extract protein/ml assay mixture. Asparthydroxamate formation was constant for about 30 min, but then declined abruptly to about 40 % of the initial rate and continued for at least a further 90 min at the lower rate. Routinely 0.2 ml volumes of extract (about I mg protein) and an incubation time of 30 min were used. Activity was greatest between pH 7-4 to 7.8, and pH 7.6 was used in the experiments described below. Details of the development of the optimal assay conditions are given elsewhere (Eccleston, 1973). Mean aspartokinase activity of eleven crude extract preparations from wild-type Methylococciis capsidatus was 9.5 nmol/mg proteinlmin (extreme values, 5 and I 3).

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The Biosynthesis of Amino Acids

Cited by 5 publications

References 298 publications

Effect of Low Temperature on Amino Acid Metabolism in Wintering Poplar

Effect of Low Temperature on Amino Acid Metabolism in Wintering Poplar

Glutamate agonists from marine algae

Inhibition by L-Threonine of Aspartokinase as a Cause of Threonine Toxicity to Methylococcus capsulatus

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