Neue Amino‐ und Ketosäuren in grünen Pflanzen und die Biosynthese der Aminosäuren

Virtanen, Artturi I.

doi:10.1002/ange.19550671404

Cited by 33 publications

(4 citation statements)

References 60 publications

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“…Since the development of Chromatographie methods, the knowledge of the alcohol soluble nitrogenous compounds occurring in plants has greatly extended by the identification of a number of substances not hitherto known to occur free, and by the recognition of a large number of compounds which were so far unidentified (Steward, Zechrius and Pollard, 1955;Virtanen, 1955;Baldwin, 1959;Nasr and Becheet, 1967;Nasr, Mohsen and Metwalli, 1972).…”

Section: Discussionmentioning

confidence: 99%

Amino Acid Pattern and Seasonal Variation in Some Marine Algae from Alexandria

Mohsen¹,

Kharboush²,

Khaleafa³

et al. 1975

Botanica Marina

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The attcntion was focussed on the amino acid pattcrn either frec or combined (in the peptide form) during the diffcrcnt scasons of the year in Laurencia papiltosa, Cystoseira barbata and Enteromorpha intestinalis. These rcpresent threc major classes of algae namcly: Rhodophyceae, Phaeophyceae and Chlorophyceae respectivcly. Since the amino acid metabolism depends on the individual alga, so it is supposed that algal classes may differ from each other in their amino acid patterns constituting the individual proteins.From this work it is easily traced that glutamine äs a whole, is gcneraüy of rare occurrence and that the free amino acid pool in Cystoseira barbata is the least one represented. It is also found that some of the free amino acids (alanine, aspartic, glutamic, glycine, and cystine-cysteine) are prescnt in each of the three aigae in approximatcly equal amounts if allowance is made for normal cxperimental errors. Considcrable diffcrcnces betwecn the percentages of certain amino acids (leucine, mcthionine, proline and glutamine) are apparcnt. It was also found, furthermore, that arg in ine, histidine, vaJine and phenylalanine are absent from the free and conju* gated amino acid pool of the three algae, within the scope of the present authors' tcchnique.

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Section: Discussionmentioning

confidence: 99%

Amino Acid Pattern and Seasonal Variation in Some Marine Algae from Alexandria

Mohsen¹,

Kharboush²,

Khaleafa³

et al. 1975

Botanica Marina

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“…Thus Jacobson (1955) has demonstrated with labeled CO^ that young excised barley roots were able to fix considerable amonnts of it in three hours, the evidence suggesting thai the synthesis resulted in the formation of malic acid. Moreover, considering the fact that various amino acids are enzymatically decarboxylated .so as lo release carbon dioxide (Virtanen 1955). the reverse process also seems possible when the equilibrium is iu favour of synhesis.…”

Section: Discussionmentioning

confidence: 99%

Cytophysiological Studies on Micrasterias

Waris

1956

Physiologia Plantarum

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“…In this laboratory a-ami no pimelic acid, ,,-hydroxy-a··aminopimelic acid, and its lactone were isolated from Asplenium septentrionale (57,58,59). The corresponding keto acids a-ketopimelic acid, ,,-hyc1roxy-a-ketopimelic acid, and its lactone--were found in the same plant (60). The formation of ,,-hydroxy-a-ketoglutaric acid by transamination from a-ketoglutaric acid and ,,-hydroxyglutamic acid was demonstrated with a homogenate of Phlox decussata, the plant in which this new amino acid was first found (61,62).…”

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confidence: 90%

Prefatory Chapter: Some Aspects of Amino Acid Synthesis in Plants and Related Subjects

Virtanen¹

1961

Annu. Rev. Plant. Physiol.

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Annu. Rev. Plant. Physiol. 1961.12:1-13 (5), with collaborators, made the important discovery that glutamic acid dehydrogenase is specific for L glutamic acid and that the reaction catalyzed by it is reversible: L-glutamic acid;::: : a-ketoglutaric acid -\-NHa The first step in reductive amination, i.e., the combining of ammonia with a-ketoglutaric acid, is not well understood even yet, but the first prod uct was assumed to be (�.iminoglutaric acid, which is then reduced by glutamic acid dehydrogenase to L-glutamic acid. This enzyme was found in all kinds of organisms: microorganisms, higher plants, and animal tissues. Later studies confirmed its decisive importance for the biosynthesis of L glutamic add. Knoop's idea of amino acid synthesis was thus realized in_ regard to L-glutamic acid, but at the same time it became evident that it was not a reaction that could explain the biosynthesis of the many different amino acids.Two amino acids in which the amino group is formed through incorpora tion of an inorganic nitrogen compound into the carbon skeleton were thus established with certainty by the end of the 1930's. I have used the term "primary" for amino acids of this type; hence "secondary" amino acids refer to either those in which the precursor already contains the amino (or imino) group, or those to which the amino group is transferred from another com pound.The synthesis of other amino acids by an analogous mechanism was not known with certainty until quite recently, even though some evidence of the "primary" nature of alanine was presented earlier. In a scheme showing the synthesis of amino acids, ten years ago I used an arrow marked with a solid line for the biosynthesis of glutamic and aspartic acids from ammonia and an arrow marked with a broken line for alanine (6). The broken line how ever, can now be drawn as a solid one since Goldman (7) recently isolated and purified from a cell-free extract of Mycobacterium tuberculosis an alanine dehydrogenase which catalyses the reaction: L-alanine+DPN+�pyruvate +NH4++DPNH.It is probable that the mechanism of action of glutamic and alanine de hydrogenases is similar. An analogous mechanism has been proposed for some other amino acids, e.g., L-aspartic acid from oxalacetic acid and am monia, but the enzyme preparations used were not purified and the reaction could not be sufficiently studied (8). Reductive amination of a-ketovaleric acid to L-norvaline, an amino acid which has never been found in higher organisms, has recently been carried out however, by crystalline glutamic acid dehydrogenase from liver (9). This reaction is possibly of no great bio logical significance, but from the biochemical point of view it is interesting, because it indicates that the 'Y-carboxyl group in a-ketoglutaric acid is not essential for the functioning of the enzyme.Even if in some organisms alanine may be formed primarily from am monia by alanine dehydrogenase, there is no proof that this amino acid

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Neue Amino‐ und Ketosäuren in grünen Pflanzen und die Biosynthese der Aminosäuren

Cited by 33 publications

References 60 publications

Amino Acid Pattern and Seasonal Variation in Some Marine Algae from Alexandria

Amino Acid Pattern and Seasonal Variation in Some Marine Algae from Alexandria

Cytophysiological Studies on Micrasterias

Prefatory Chapter: Some Aspects of Amino Acid Synthesis in Plants and Related Subjects

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