Ammonia Assimilation and Metabolite Transport in Isolated Chloroplasts. I. Kinetic Measurement of 2-Oxoglutarate and Malate Uptake Via the 2-Oxoglutarate Translocator in Oat and Spinach Chloroplasts

1992 ◽  
Vol 19 (6) ◽  
pp. 653 ◽  
Author(s):  
JW Yu ◽  
KC Woo
Keyword(s):  
Double Layer ◽  
Ammonia Assimilation ◽  
Kinetic Properties ◽  
Kinetic Measurement ◽  
Transport Activity ◽  
Metabolite Transport ◽  
Spinach Chloroplasts ◽  
Dicarboxylate Transport ◽  
Push And Pull ◽  
Isolated Chloroplasts

The stable double-layer silicone centrifugation system was used to determine the kinetic properties of the 2-oxoglutarate (2-OG) translocator in isolated oat and spinach chloroplasts. The uptake of [14C]2-OG and [14C]malate via the 2-OG translocator were measured in the presence of 20 mM glutamate in chloroplasts preloaded with unlabelled 2-OG. The characteristics of the general dicarboxylate (Dct) translocator were also determined using chloroplasts preloaded with glutamate. The Vmax values obtained for transport activity via the 2-OG translocator in oat and spinach chloroplasts exceeded 150 μmol mg-1 Chl h-1 and for the Dct translocator less than 100 μmol mg-1 Chl h-1. The K� (malate) values of the 2-OG and Dct translocators also showed large differences in the two species. In spinach chloroplasts they were 2.7 and 0.6 mM for the 2-OG and Dct translocators respectively whereas, in oat chloroplasts the corresponding values were 2.7 and 1.4 mM. This suggests that, in spinach, malate would be transported into the chloroplasts preferentially via the Dct translocator, thus providing a kinetic basis for the 'push and pull' mechanism proposed for dicarboxylate transport during photorespiratory NH3 recycling in the 2-translocator model.

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.

Inhibition of Protein Synthesis in Chloroplasts from Plant Cells by Virginiamycin

1979 ◽  
Vol 34 (12) ◽  
pp. 1195-1198 ◽  
Author(s):  
C. Cocito ◽  
O. Tiboni ◽  
F. Vanlinden ◽  
O. Ciferri
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Synergistic Effect ◽  
Plant Cells ◽  
Inhibitory Effect ◽  
Spinach Chloroplasts ◽  
Inhibition Of Protein Synthesis ◽  
Isolated Chloroplasts

Abstract The light-driven incorporation of amino acids by isolated spinach chloroplasts is inhibited by the M component (VM) and not by the S component (VS) of virginiamycin. This inhibitory effect is partially reversible. In chloroplast extracts, poly(U)-directed polyphenylalanine formation is strongly inhibited by VM and not by VS. The in vivo synergistic effect of VM and VS observed in bacteria and algae, does not occur in isolated chloroplasts and chloroplast extracts.

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 Polarographic Study of Ammonia Assimilation by Isolated Chloroplasts

1977 ◽  
Vol 60 (4) ◽  
pp. 504-508 ◽  
Author(s):  
John W. Anderson ◽  
James Done
Keyword(s):  
Ammonia Assimilation ◽  
Polarographic Study ◽  
Isolated Chloroplasts

Effects of chronic metabolic acidosis on Na(+)-H+ exchangers in LLC-PK1 renal epithelial cells

1992 ◽  
Vol 263 (1) ◽  
pp. F83-F88 ◽  
Author(s):  
P. Igarashi ◽  
M. I. Freed ◽  
M. B. Ganz ◽  
R. F. Reilly
Keyword(s):  
Metabolic Acidosis ◽  
Epithelial Cells ◽  
Kinetic Properties ◽  
Control Medium ◽  
Transport Activity ◽  
Medium Ph ◽  
Transcript Levels ◽  
Renal Epithelial Cells ◽  
Chronic Metabolic Acidosis ◽  
Stimulation Of

Porcine renal epithelial cells (LLC-PK1/clone 4) have Na(+)-H+ exchangers with different kinetic properties in their apical and basolateral membranes. cDNAs encoding the basolateral Na(+)-H+ exchanger were recently cloned. To determine whether expression of the basolateral Na(+)-H+ exchanger was affected by chronic metabolic acidosis, LLC-PK1/clone 4 cells were grown on permeant supports and incubated in control medium (pH 7.4) or acid medium (pH 6.9). After 48 h, Na(+)-H+ exchanger transport activity was measured as N-ethyl-N-isopropylamiloride (EIPA)-sensitive 22Na+ influx. Acidification caused an 84% stimulation of the transport activity of the basolateral Na(+)-H+ exchanger. The apical Na(+)-H+ exchanger was stimulated 72%, and there was no change in the EIPA-insensitive 22Na+ flux across either membrane. Stimulation of Na(+)-H+ exchange was not due to differences in intracellular pH at the time transport was assayed. To determine whether there were corresponding changes in transcript levels, poly(A)+ RNA was isolated from LLC-PK1 cells and hybridized with a cDNA encoding the basolateral Na(+)-H+ exchanger. Levels of transcripts encoding the basolateral Na(+)-H+ exchanger were increased 70% after 48 h of acidification, and there were no changes in transcripts encoding cytoskeletal gamma-actin or glyceraldehyde-3-phosphate dehydrogenase. We conclude that conditions simulating chronic metabolic acidosis coordinately increase the transport activity and transcript levels of the basolateral Na(+)-H+ exchanger in porcine renal epithelial cells.

Exhaustive-exercise-induced oxidative stress alteration of erythrocyte oxygen release capacity

2018 ◽  
Vol 96 (9) ◽  
pp. 953-962 ◽  
Author(s):  
Yanlian Xiong ◽  
Yanlei Xiong ◽  
Yueming Wang ◽  
Yajin Zhao ◽  
Yaojin Li ◽  
...  
Keyword(s):  
Carbonic Anhydrase ◽  
Band 3 ◽  
Anion Transport ◽  
Kinetic Properties ◽  
Oxygen Release ◽  
Transport Activity ◽  
Running Exercise ◽  
Release Capacity ◽  
Anion Transport Activity ◽  
2,3 Dpg

The aim of the present study was to explore the effect of exhaustive running exercise in the oxygen release capacity of rat erythrocytes. Rats were divided into sedentary control, moderate running exercise, and exhaustive running exercise groups. The thermodynamic and kinetic properties of the erythrocyte oxygen release process of the different groups were tested. We also determined the degree of band-3 oxidation and phosphorylation, anion transport activity, and carbonic anhydrase isoform II activity. Biochemical studies suggested that exhaustive running significantly increased oxidative injury parameters in thiobarbituric acid reactive substances and methaemoglobin levels. Furthermore, exhaustive running significantly decreased anion transport activity and carbonic anhydrase isoform II activity. Thermodynamic analysis indicated that erythrocytes oxygen release ability also significantly increased due to elevated 2,3-DPG level after exhaustive running. Kinetic analysis indicated that exhaustive running resulted in significantly decreased T50 value. We presented evidence that exhaustive running remarkably impacted thermodynamic and kinetic properties of RBC oxygen release. In addition, changes in 2,3-DPG levels and band-3 oxidation and phosphorylation could be the driving force for exhaustive-running-induced alterations in erythrocyte oxygen release thermodynamic and kinetic properties.

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