ENZYMIC ACTIVITIES OF SUBCELLULAR PARTICLES FROM LEAVES: IV. PHOTOSYNTHETIC PHOSPHORYLATION AND PHOTOSYNTHESIS BY ISOLATED CHLOROPLASTS FROM PEA LEAVES

1959 ◽  
Vol 37 (6) ◽  
pp. 1217-1225 ◽  
Author(s):  
R. M. Smillie ◽  
G. Krotkov
Keyword(s):  
Carbon Dioxide ◽  
Inorganic Phosphate ◽  
Fixed Carbon ◽  
Spinach Chloroplasts ◽  
Green Pea ◽  
Isolated Chloroplasts

Chloroplasts were isolated in 0.35 M NaCl from green pea leaves. Such preparations formed ATP photosyathetically from AMP or ADP and inorganic phosphate. The conditions and cofactors of this reaction were studied. The rates of photosynthetic phosphorylation by isolated pea chloroplasts were compared with photosynthetic phosphorylation by spinach chloroplasts and with photosynthesis by intact pea leaves. The isolated pea chloroplasts also photosynthetically fixed carbon dioxide. The possible roles of chloroplasts and mitochondria in cellular phosphorylations are discussed.

scholarly journals Photosynthesis by isolated chloroplasts. Reversal of orthophosphate inhibition by Calvin-cycle intermediates

1968 ◽  
Vol 107 (1) ◽  
pp. 89-95 ◽  
Author(s):  
W. Cockburn ◽  
D. A. Walker ◽  
C. W. Baldry
Keyword(s):  
Carbon Dioxide ◽  
Metabolic Control ◽  
Oxygen Evolution ◽  
Calvin Cycle ◽  
Dihydroxyacetone Phosphate ◽  
Spinach Chloroplasts ◽  
Diphosphate Glucose ◽  
Kinetics Of ◽  
Related Compounds ◽  
Isolated Chloroplasts

1. The orthophosphate inhibition of photosynthesis by isolated spinach chloroplasts can be reversed by 3-phosphoglycerate, dihydroxyacetone phosphate, glyceraldehyde 3-phosphate, fructose 6-phosphate and fructose 1,6-diphosphate. 2. Metabolically related compounds such as ribulose 1,5-diphosphate, glucose 6-phosphate, 6-phosphogluconate and phosphoenolpyruvate are ineffective. 3. The kinetics of reversal are characteristic of the intermediate used, but, in each instance, the onset of oxygen evolution is accompanied by a carbon dioxide fixation and except with 3-phosphoglycerate the stoicheiometry is close to unity. 4. The nature of orthophosphate inhibition and its reversal is discussed in relation to metabolic control of photosynthesis.

HYDROLYSIS OF LECITHIN BY PLANT PLASTID ENZYMES

1955 ◽  
Vol 33 (1) ◽  
pp. 575-589 ◽  
Author(s):  
Morris Kates
Keyword(s):  
Phosphatidic Acid ◽  
Inorganic Phosphate ◽  
Organic Phosphate ◽  
Water Soluble ◽  
Lag Phase ◽  
Carrot Root ◽  
First Order ◽  
Spinach Chloroplasts ◽  
Egg Lecithin ◽  
Hydrolysis Of

Enzymatic liberation of choline from egg lecithin by plastid fractions from sugar beet, spinach, and cabbage leaves and from carrot root was a rapid, first order reaction (up to 70% hydrolysis), and was not preceded by a lag phase. None of the choline-containing products of lecithin degradation (lysolecithin, glycerylphosphorylcholine, or phosphorylcholine) lost choline on incubation with spinach chloroplasts. Inorganic phosphate liberation from lecithin by the plastids was preceded by a lag phase and was much slower than choline liberation. Spinach chloroplasts catalyzed the liberation of inorganic phosphate from L-α-phosphatidic acid and from L-α-glycerophosphate. The water-soluble organic phosphate liberated from lecithin by spinach chloroplasts was identified chromatographically as phosphorylcholine. The ether-soluble organic phosphate produced during the hydrolysis of egg lecithin by carrot plastids was isolated and identified as L-α-phosphatidic acid. These observations suggest that the enzymatic hydrolysis of lecithin by plant plastids involves the following reactions: (1) lecithin → L-α-phosphatidic acid + choline; (2) L-α-phosphatidic acid → inorganic phosphate + diglyceride and/or (3) L-α-phosphatidic acid → glycerophosphate + fatty acids and (4) glycerophosphate → inorganic phosphate + glycerol; and (5) lecithin → phosphorylcholine + diglyceride. The L-α-structure for egg lecithin was confirmed.

scholarly journals Effects of Inorganic Phosphate on the Light Dependent Thylakoid Energization of Intact Spinach Chloroplasts

1989 ◽  
Vol 91 (1) ◽  
pp. 221-226 ◽  
Author(s):  
Dieter Heineke ◽  
Mark Stitt ◽  
Hans W. Heldt
Keyword(s):  
Inorganic Phosphate ◽  
Spinach Chloroplasts

Ammonia Assimilation and Metabolite Transport in Isolated Chloroplasts. II. Malate Stimulates Ammonia Assimilation in Chloroplasts Isolated From Leaves of Dicotyledonous but Not Monocotyledonous Species

1992 ◽  
Vol 19 (6) ◽  
pp. 659 ◽  
Author(s):  
JW Yu ◽  
KC Woo
Keyword(s):  
Nutrient Solution ◽  
The Other ◽  
Ammonia Assimilation ◽  
O2 Evolution ◽  
Evolution System ◽  
Metabolite Transport ◽  
Spinach Chloroplasts ◽  
Counter Ion ◽  
High Nutrient ◽  
Isolated Chloroplasts

Malate stimulated NH3 assimilation, as determined by a (2-oxoglutarate, NH3)-dependent O2 evolution system, by up to 3-fold in chloroplasts isolated from leaves of dicot but not monocot species. This difference was apparently correlated with the endogenous metabolite pools present in these chloroplast preparations. During NH3 assimilation the glutamate and glutamine pools were large in spinach (dicot) but small in oat chloroplasts. The reverse was the case for the 2-oxoglutarate (2-OG) pool. The addition of malate substantially increased the glutamate, glutamine and 2-OG pools in spinach chloroplasts but had little effect in oat chloroplasts. This suggests that the supply of 2-OG was apparently limiting NH3 assimilation in spinach chloroplasts. Malate increased this supply and, consequently, stimulated NH3 assimilation. On the other hand, NH3 assimilation in oat chloroplasts seemed to be limited by the supply of glutamate and glutamine which could not be overcome by the addition of malate. Chloroplasts were also isolated from oat seedlings watered with high nutrient solution. The rates of NH3 assimilation in these organelles exceeded those obtained in spinach chloroplasts. But the addition of malate had little effect on (2-OG, NH3)-dependent O2 evolution in these oat chloroplasts. Since malate did not inhibit this activity it is conceivable that it still might play a role, albeit a 'passive' role, in serving as a counter-ion for 2-OG uptake via the 2-OG translocator and glutamate export via the Dct translocator during NH3 assimilation.

The award of medals by the President, Sir George Porter, at the Anniversary Meeting, 30 November 1987

1988 ◽  
Vol 417 (1852) ◽  
pp. 1-5
Keyword(s):  
Carbon Dioxide ◽  
Electron Transfer ◽  
Chemical Analysis ◽  
Water Oxidation ◽  
Carbon Dioxide Reduction ◽  
Electron Transfer Pathway ◽  
Starting Point ◽  
Main Pathway ◽  
Isolated Chloroplasts ◽  
Detailed Chemical

The Copley Medal is awarded to Dr R. Hill, F. R. S., in recognition of his pioneering contributions to the understanding of the nature and mechanism of the main pathway of electron transport in photosynthesis. Almost fifty years ago Hill made the first important discovery that allowed detailed chemical analysis of the pathways of photosynthesis, when he demon­strated the light-driven oxidation of water by isolated chloroplasts, and this made it possible to study water oxidation separately from carbon-dioxide reduction. This was the starting point in the elucidation of the electron-transfer pathway in photosynthesis, and in 1951 Hill, with R. Scarisbrick, uncovered the first com­ponent in the chain when they discovered cytochrome and established its key properties. Subsequently, with H. E. Davenport, Hill discovered the second com­ponent of the chain, shown later by others to be ferredoxin. With F. Bendall he formulated the ‘Z-scheme’ to describe the mechanism of electron transfer in photosynthesis in chloroplasts, which showed the relation between the photochemically driven elements and conventional electron-transfer chains found in other biological systems. This proposal brought great clarity to the field and set the scene for further detailed elucidation of the mechanisms.

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