Role of cyclic photophosphorylation in photosynthetic carbon dioxide assimilation by isolated chloroplasts

1972 ◽  
Vol 267 (1) ◽  
pp. 111-124 ◽  
Author(s):  
Peter Schürmann ◽  
Bob B. Buchanan ◽  
Daniel I. Arnon
Keyword(s):  
Carbon Dioxide ◽  
Carbon Dioxide Assimilation ◽  
Photosynthetic Carbon ◽  
Cyclic Photophosphorylation ◽  
Isolated Chloroplasts

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.

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.

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.

Chloride Requirement for Oxygen Evolution in Photosynthesis

1963 ◽  
Vol 18 (9) ◽  
pp. 683-688 ◽  
Author(s):  
J. M. Bové ◽  
Colette Bové ◽  
F. R. Whatley ◽  
Daniel I. Arnon
Keyword(s):  
Oxygen Evolution ◽  
Photochemical Reactions ◽  
Photosynthetic Oxygen Evolution ◽  
Ferricyanide Reduction ◽  
Atp Formation ◽  
Cyclic Photophosphorylation ◽  
Photosynthetic Oxygen ◽  
Isolated Chloroplasts ◽  
Spinach Leaves

The role of chloride in photosynthetic oxygen evolution was reinvestigated by determining the effect of this ion on photochemical reactions of chloroplasts in which oxygen either is or is not produced. The chloroplasts used were isolated from normal spinach leaves. The level of chloride in the reaction mixture was controlled by washing the isolated chloroplasts and by avoiding a chloride contamination from the water and chemicals used. Chloride was found to be essential for each of the photochemical reactions of chloroplasts in which oxygen is produced. These included (a) photoreduction of TPN, (b) photophosphorylation of the noncyclic type in which TPN or ferricyanide reduction is coupled with ATP formation and (c) photophosphorylation of the aerobic, “pseudocyclic” type in which oxygen production occurs but is masked by an equal oxygen consumption. No chloride requirement was found for the anaerobic, cyclic photophosphorylation in which oxygen is not produced. These results support the view that chloride is an essential cofactor for oxygen evolution in photosynthesis.

scholarly journals Role of Potassium in Carbon Dioxide Assimilation in Medicago sativa L

1979 ◽  
Vol 63 (5) ◽  
pp. 878-881 ◽  
Author(s):  
Timothy R. Peoples ◽  
David W. Koch
Keyword(s):  
Carbon Dioxide ◽  
Medicago Sativa ◽  
Carbon Dioxide Assimilation ◽  
Medicago Sativa L

scholarly journals Calvin-cycle intermediates in relation to induction phenomena in photosynthetic carbon dioxide fixation by isolated chloroplasts

1966 ◽  
Vol 101 (3) ◽  
pp. 642-646 ◽  
Author(s):  
CW Baldry ◽  
DA Walker ◽  
C Bucke
Keyword(s):  
Carbon Dioxide ◽  
Calvin Cycle ◽  
Carbon Dioxide Fixation ◽  
Chloroplast Envelope ◽  
Induction Periods ◽  
New Synthesis ◽  
Photosynthetic Carbon ◽  
Sugar Phosphates ◽  
Isolated Chloroplasts ◽  
Additional Fixation

1. Induction periods in carbon dioxide fixation by isolated pea chloroplasts were shortened by small quantities of Calvin-cycle intermediates. The additional fixation was larger than that which would have followed direct stoicheiometric conversion into ribulose 1,5-diphosphate. 2. When chloroplasts were illuminated in the absence of added substrates (other than carbon dioxide) soluble products were formed in the medium that stimulated fixation by fresh chloroplasts. 3. The induction periods were lengthened by washing the chloroplasts. Addition of catalytic quantities of Calvin-cycle intermediates then decreased the induction periods to their previous values. 4. The induction period was extended by a decrease in temperature but was largely unaffected by a decrease in light-intensity that was sufficient to decrease the maximum rate. 5. It is concluded that the lag periods are a consequence of the loss of Calvin-cycle intermediates, such as sugar phosphates, through the intact chloroplast envelope and that these losses can be made good by new synthesis from carbon dioxide in the reactions of the Calvin cycle.

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