THE ROLE OF KETO ACIDS IN PHOTOSYNTHETIC CARBON DIOXIDE ASSIMILATION

1956 ◽  
Vol 34 (1) ◽  
pp. 511-519 ◽  
Author(s):  
G. H. N. Towers ◽  
D. C. Mortimer
Keyword(s):  
Carbon Dioxide ◽  
Amino Acids ◽  
Sugar Beet ◽  
Aspartic Acid ◽  
Pyruvic Acid ◽  
Carbon Dioxide Assimilation ◽  
Free Air ◽  
Keto Acids ◽  
Photosynthetic Carbon

Of the keto acids identified in leaves of sugar beet and other plants exposed to C14O2, pyruvic acid was found to be the only one labelled in light periods up to 45 sec. α-Ketoglutaric and glyoxylic acids became radioactive after about 45 sec. Radioactive hydroxypyruvate was not identified under these conditions and labelled oxaloacetate was detected only in trace amounts after 60 sec. in Scenedesmus. In contrast glycine and serine were labelled after 10 sec. under comparable conditions and aspartic acid was appreciably labelled after 30 sec. The effect on the radioactivity of the keto acids of an additional period intracer-free air, with and without light, as well as the dark incorporation of C14O2 was studied. These results are discussed in relation to the role of the ketoacids in photosynthesis. It is concluded that the synthesis of amino acids such as glycine, serine, and aspartic acid may be effected by mechanisms other than transamination in green leaves in the light.

THE ROLE OF KETO ACIDS IN PHOTOSYNTHETIC CARBON DIOXIDE ASSIMILATION

1956 ◽  
Vol 34 (3) ◽  
pp. 511-519 ◽  
Author(s):  
G. H. N. Towers ◽  
D. C. Mortimer
Keyword(s):  
Carbon Dioxide ◽  
Amino Acids ◽  
Sugar Beet ◽  
Aspartic Acid ◽  
Pyruvic Acid ◽  
Carbon Dioxide Assimilation ◽  
Free Air ◽  
Keto Acids ◽  
Photosynthetic Carbon

Of the keto acids identified in leaves of sugar beet and other plants exposed to C14O2, pyruvic acid was found to be the only one labelled in light periods up to 45 sec. α-Ketoglutaric and glyoxylic acids became radioactive after about 45 sec. Radioactive hydroxypyruvate was not identified under these conditions and labelled oxaloacetate was detected only in trace amounts after 60 sec. in Scenedesmus. In contrast glycine and serine were labelled after 10 sec. under comparable conditions and aspartic acid was appreciably labelled after 30 sec. The effect on the radioactivity of the keto acids of an additional period intracer-free air, with and without light, as well as the dark incorporation of C14O2 was studied. These results are discussed in relation to the role of the ketoacids in photosynthesis. It is concluded that the synthesis of amino acids such as glycine, serine, and aspartic acid may be effected by mechanisms other than transamination in green leaves in the light.

IODOACETATE INHIBITION OF PHOTOSYNTHETIC CARBON DIOXIDE ASSIMILATION IN SUGAR BEET AND SOYBEAN LEAVES

1960 ◽  
Vol 38 (4) ◽  
pp. 623-634 ◽  
Author(s):  
D. C. Mortimer
Keyword(s):  
Carbon Dioxide ◽  
Sugar Beet ◽  
Aspartic Acid ◽  
Glyceric Acid ◽  
Carbon Dioxide Assimilation ◽  
Alternate Pathway ◽  
Acid Incorporation ◽  
Photosynthetic Carbon ◽  
Phosphoglyceric Acid ◽  
Soybean Leaves

When the petioles of freshly excised sugar beet or soybean leaves were immersed in dilute iodoacetate solutions, the rates of photosynthetic carbon dioxide assimilation were reduced and characteristic changes in the distribution of assimilated C14 were observed. Inhibited sugar beet leaves accumulated C14 in phosphoglyceric acid (PGA) and aspartic acid, but did not incorporate C14 into glyceric acid. Inhibited soybean leaves continued to form glyceric acid, but did not incorporate C14 into PGA and only trace amounts into aspartic acid. Incorporation of C14 into sucrose by the sugar beet leaf ceased when the assimilation of carbon dioxide was reduced below 1/10th of normal, while soybean leaves still formed sucrose at that level of inhibition. It was concluded from these and other data that the mechanisms for photosynthetic carbon dioxide assimilation in the two species were different. The iodoacetate-sensitive, PGA-glyceraldehyde-3-phosphate reduction, which could account for only part of the assimilation by sugar beet leaves, did not appear to be utilized by soybean leaves. An alternate pathway for the reduction of carbon dioxide to the carbohydrate level is postulated to account for the assimilation patterns observed in the two species.

THE BIOGENESIS OF ALKALOIDS: XVII. FURTHER STUDY OF THE ROLE OF ORNITHINE IN THE BIOGENESIS OF STACHYDRINE

1956 ◽  
Vol 34 (12) ◽  
pp. 1704-1708 ◽  
Author(s):  
Arthur Morgan ◽  
Léo Marion
Keyword(s):  
Amino Acids ◽  
Glutamic Acid ◽  
Medicago Sativa ◽  
Aspartic Acid ◽  
The Other ◽  
Feeding Experiment ◽  
Seed Formation ◽  
Keto Acids ◽  
Medicago Sativa L

Earlier attempts to feed ornithine-2-C14 to Medicago sativa L. Grimm had failed to produce any labelled stachydrine. Repetition of the work has confirmed this result, and a study of the amino acids present in the plant has shown that the proline also was inactive. Feeding pyridoxine with ornithine-2-C14 to the plant did not produce active stachydrine, but gave rise to radioactive proline. Of the other amino acids present, glycine, aspartic acid, and glutamic acid were also active. A similar feeding experiment with radioactive ornithine and pyridoxine, using older plants, also failed to produce active stachydrine although, as before, the proline was active and so was the keto acids fraction.The results seem to indicate that ornithine may be the precursor of stachydrine, but that the transformation to proline and the methylation to the alkaloid occur at a later stage of growth, possibly at seed formation.

scholarly journals Enhancement of aromatase activity by D-aspartic acid in the ovary of the lizard Podarcis s. sicula

Reproduction ◽  
2001 ◽  
pp. 803-808 ◽  
Author(s):  
L Assisi ◽  
V Botte ◽  
A D'Aniello ◽  
MM Di Fiore
Keyword(s):  
Amino Acids ◽  
Aspartic Acid ◽  
Reproductive Cycle ◽  
Catalytic Properties ◽  
Ovarian Tissue ◽  
Experimental Treatment ◽  
Tissue Homogenate ◽  
Aromatase Activity

The present study investigated the role of D-aspartic acid (D-Asp) in ovarian steroidogenesis and its effect on aromatase activity in the lizard, Podarcis s. sicula. It was determined that D-Asp concentrations vary significantly during phases of the reproductive cycle: they vary inversely with testosterone concentrations and directly with oestradiol concentrations in the ovary and plasma. Experimental treatment showed that administration of D-Asp induces a decrease in testosterone and an increase in oestradiol, and that treatment with other amino acids (L-Asp, D-Glu and D-Ala) instead of D-Asp has no effects. Experiments in vitro confirmed these results. Furthermore, these experiments showed an increase in aromatase activity, as the addition of D-Asp either to fresh ovarian tissue homogenate or to acetonic powder of ovarian follicles induced a significant increase in the conversion of testosterone to oestradiol. Aromatase activity is four times greater in the presence of D-Asp than in its absence. However, almost equivalent values of the two K(m) values (both approximately 25 nmol l(-1)) indicate that aromatase has the same catalytic properties in both cases.

scholarly journals Photosynthesis by isolated chloroplasts. Inhibition by dl-glyceraldehyde of carbon dioxide assimilation

1972 ◽  
Vol 128 (5) ◽  
pp. 1147-1157 ◽  
Author(s):  
D. M. Stokes ◽  
D. A. Walker
Keyword(s):  
Carbon Dioxide ◽  
Carbon Assimilation ◽  
Photosynthetic Electron Transport ◽  
O2 Evolution ◽  
Appreciable Effect ◽  
Carbon Dioxide Assimilation ◽  
Photosynthetic Carbon ◽  
Photosynthetic Carbon Assimilation ◽  
Isolated Chloroplasts ◽  
Spinach Leaves

Photosynthetic carbon assimilation and associated CO2-dependent O2 evolution by chloroplasts isolated from pea shoots and spinach leaves is almost completely inhibited by 10mm-dl-glyceraldehyde. The inhibitor is without appreciable effect on photosynthetic electron transport, photophosphorylation, the carboxylation of ribulose 1,5-diphosphate or the reduction of 3-phosphoglycerate, but apparently blocks the conversion of triose phosphate into ribulose 1,5-diphosphate.

Exploring the role of ions and amino acids in directing the growth of minerals from solution

2008 ◽  
Vol 72 (1) ◽  
pp. 273-276 ◽  
Author(s):  
S. Piana ◽  
F. Jones ◽  
Z. Taylor ◽  
P. Raiteri ◽  
J. D. Gale
Keyword(s):  
Amino Acids ◽  
Computer Simulation ◽  
Free Energy ◽  
Aspartic Acid ◽  
Morphology Control ◽  
New Approach ◽  
Activation Free Energy

AbstractThe influence of both sulphate ions and aspartic acid on directing the growth of baryte has been explored using computer simulation. Both species are found to significantly reduce the activation free-energy to growth under appropriate conditions, with the influence of sulphate being surface specific. This offers the potential for a new approach to morphology control without inhibition that may have implications for biomineralization.

Studies in the respiratory and carbohydrate metabolism of plant tissues - Experimental studies of the formation of carbon dioxide and of the changes in lactic acid, sucrose and in certain fractions of keto-acids in potato tubers in air following anaerobic conditions

1953 ◽  
Vol 141 (904) ◽  
pp. 321-337 ◽  
Keyword(s):  
Carbon Dioxide ◽  
Lactic Acid ◽  
Pyruvic Acid ◽  
Experimental Studies ◽  
Krebs Cycle ◽  
Plant Tissues ◽  
Potato Tubers ◽  
Anaerobic Conditions ◽  
Co2 Output ◽  
Keto Acids

Barker A Saifl (1953 b ), suggested that the initial rapid increase and the subsequent slower decrease in the CO 2 output of potatoes in air after a peroid under anaerobic conditions might be partly related to a quick formation of pyruvic acid from the accumulated lactic acid and to the respiration of the Pyruvic acid via krebs cycle (krebs & johnson 1937; krebs 1952). Information bearing on the associated changes in pyruvic and α-ketoglutaric acid has now been obtained using a technique (Friedemann & Haugen 1943; Friedemann 1950) which while not fully specific gives values that are known to include true pyruvic acid and true α-ketoglutaric acid as well as non-pyruvic and non-α-ketoglutaric acid material respectively. Associated with the loss of Lactic acid in air after nitrogen and the accompanying increase followed by a decrease in the CO 2 output, Mentioned above, there was first a rapid increase in the content of 'pyruvic' and 'α-ketoglutaric acid' and then a prolonged decrease in these fractions. The analysis of the interrelation between the loss of lactic acid and the production of CO 2 and of the keto-acids, and between the changes in the rate of CO2 output and the changes in the concentration of the keto-acids and of sucrose, is taken up in the next paper in this series (Barker & Mapson 1953).

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