共查询到20条相似文献,搜索用时 15 毫秒
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Ivan Pacold Louise E. Anderson 《Biochemical and biophysical research communications》1973,51(1):139-143
Pea () leaf cytoplasmic and chloroplast 3-P-glyceric acid kinases are controlled by adenylate energy charge. In the light, when energy charge is high, the chloroplast enzyme will be stimulated in the direction of the Calvin cycle, and the glycolytic activity of the cytoplasmic kinase will be inhibited. In the dark when energy charge is lower, both enzymes may participate in the generation of ATP. 相似文献
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Maize mesophyll chloroplasts loaded with radioactively labeled 3-phosphoglycerate or phosphoenolpyruvate exchange these compounds for externally provided inorganic phosphate, 3-phosphoglycerate, phosphoenolpyruvate, and dihydroxyacetone phosphate. These exchanges are inhibited by pyridoxal phosphate. 3-Phosphoglycerate uptake, which leads to accumulation of this substance in the stroma, is competitively inhibited by inorganic phosphate and phosphoenolpyruvate. These results are consistent with the transport of 3-phosphoglycerate, phosphoenolpyruvate, inorganic phosphate, and dihydroxyacetone phosphate being mediated by a common carrier (the phosphate translocator). The activation energy of 3-phosphoglycerate uptake as determined from its temperature dependence is 19.5 kcal (4–15 °C). In isolated chloroplasts malate and phosphoenolpyruvate production from oxalacetate and pyruvate, respectively, is inhibited by 3-phosphoglycerate, the extent of inhibition being dependent on the relative concentrations of inorganic phosphate and 3-phosphoglycerate. We propose that 3-phosphoglycerate from bundle-sheath cells may serve as a feedback regulator of mesophyll cell photosynthesis. 相似文献
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Glycerate-3-P inhibits CO2 fixation of isolated spinach chloroplats at concentrations higher than 1 mM but does not inhibit O2 evolution. Glycerate-3-P inhibition of photosynthesis is not overcome by higher bicarbonate concentrations. 相似文献
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R. Brändén T. Nilsson S. Styring 《Biochemical and biophysical research communications》1980,92(4):1297-1305
A sensitive and reliable method to determine the stereochemical composition of 3-phosphoglyceric acid is presented. Results obtained with this method show that 3-phosphoglyceric acid formed in the ribulose-1,5-bisphosphate carboxylase reaction is a mixture of 10% L-3-PGA and 90% D-3-PGA. 相似文献
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Hollender D Jakusch T Buhsina S Aboukais A Abi Aad E Kiss T 《Journal of inorganic biochemistry》2001,85(4):245-251
The complexes formed between D-3-phosphoglyceric acid and H(+), Cu(II) and VO(IV) were studied by pH-potentiometric and spectral (UV-Vis, EPR and CD) methods in order to describe the speciation of the metal ions and to determine the most probable binding modes in the complexes formed in these systems. The results show that, in the pH range between 2 and 4, mononuclear 1:1 complexes are formed through bidentate (MAH) or tridentate (MA) coordination of the ligand. At higher pH, when the proton competition for the central alcoholic-OH function decreases, alcoholate-bridged dinuclear species of composition M(2)A(2)H(-n) (n=1-3) become predominant. VO(IV) seems to have a higher tendency than Cu(II) to form such dinuclear complexes. 相似文献
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Adenosine diphosphate glucose pyrophosphorylase (AGPase; EC 2.7.7.27) synthesizes the starch precursor, ADP-glucose. It is a rate-limiting enzyme in starch biosynthesis and its activation by 3-phosphoglyceric acid (3PGA) and/or inhibition by inorganic phosphate (Pi) are believed to be physiologically important. Leaf, tuber and cereal embryo AGPases are highly sensitive to these effectors, whereas endosperm AGPases are much less responsive. Two hypotheses can explain the 3PGA activation differences. Compared to leaf AGPases, endosperm AGPases (i) lack the marked ability to be activated by 3PGA or (ii) they are less dependent on 3PGA for activity. The absence of purified preparations has heretofore negated answering this question. To resolve this issue, heterotetrameric maize ( Zea mays L.) endosperm and potato ( Solanum tuberosum L.) tuber AGPases expressed in Escherichia coli were isolated and the relative amounts of enzyme protein were measured by reaction to antibodies against a motif resident in both small subunits. Resulting reaction rates of both AGPases are comparable in the presence but not in the absence of 3PGA when expressed on an active-protein basis. We also placed the potato tuber UpReg1 mutation into the maize AGPase. This mutation greatly enhances 3PGA sensitivity of the potato AGPase but it has little effect on the maize AGPase. Thirdly, lysines known to bind 3PGA in potato tuber AGPase, but missing from the maize endosperm AGPase, were introduced into the maize enzyme. These had minimal effect on maize endosperm activity. In conclusion, the maize endosperm AGPase is not nearly as dependent on 3PGA for activity as is the potato tuber AGPase. 相似文献
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The aim of this work was to test the hypothesis that changes in cytosolic 3-phosphoglyceric acid (3-PGA) content can regulate the rate of starch synthesis in potato (Solanum tuberosum L.) tubers. The amount of 3-PGA was increased by expressing bacterial phosphofructokinase (PFK; EC 2.7.1.11) in transgenic potato tubers. The resultant 3-fold increase in PFK activity was accompanied by an increase in metabolites downstream of PFK, including a 3-fold increase in 3-PGA. There was also a decrease in metabolites upstream of PFK, most notably of glucose-6-phosphate. The increase in 3-PGA did not affect the amount of starch that accumulated in developing tubers, nor its rate of synthesis in tuber discs cut from developing tubers. This suggests that changes in cytosolic 3-PGA may not affect the rate of starch synthesis under all circumstances. We propose that in this case, a decrease in glucose-6-phosphate (which is transported into the amyloplast as a substrate for starch synthesis) may be sufficient to counteract the effect of increased 3-PGA. 相似文献
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- In the presence of NADP+ and Mg++, the bundle sheath strandsisolated from corn (Zea mays) leaves by cellulase treatmentsdecarboxylated malate in the light at an initial rate (200 µmoles/mgchl.hr), which was sufficient to account for photosyntheticCO2 fixation in intact leaves. This rate gradually slowed downand then stopped. The final level of the malate decarboxylatedwas approximately equal to the amount of NADP+ added.
- Rapidand continued decarboxylation of malate was observed whenNADP+,3-phosphoglyceric acid and ATP (and Mg++) were addedtogether.The addition of ADP instead of ATP showed a similareffect.Light did not show any effect on the malate decarboxylationin the presence of ATP or ADP.
- When malate was added to thebundle sheath strands in the presenceof exogenous NADP+ NADP+was rapidly reduced. The reductionstopped after 2 min when,73% of the added NADP+ was reduced.The further addition of3-phosphoglyceric acid and ATP broughtabout a decrease in theNADPH-level, which rose again to attaina new steady level.
- The transfer of radioactivity from (1-14C-3-phosphoglycericacid to dihydroxyacetone phosphate in the bundle sheath strandsin the presence of ATP and NADP+ was greatly enhanced by theaddition of malate.
- In the presence of ribose 5-phosphateand ATP, the rate of 14C-transferfrom (4-14C)-malate to theintermediates of the reductive pentosephosphate cycle was equalto that of 14CO2 fixation in the light.
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Ravendra Pal Singh 《Journal of biosciences》1984,6(2):203-212
Rapidly metabolizable compounds such as glucose or glycerol were not utilized byBacillus megaterium in the absence of manganese when grown in the supplemented nutrient broth medium. Under these conditions, growth ceased at
low cell titre, 3-phosphoglyceric acid accumulated inside the cells and normal sporulation process was arrested. Addition
of manganese to the medium caused disappearance of 3-phosphoglyceric acid, growth resumed and normal sporulation was observed.
Synthesis of 3-phosphoglyceric acid occurred only in the mother cell compartments and it was transported for accumulation
inside the forespores ofBacillus megaterium when grown in supplemented nutrient broth medium. Incubation of forespores in the presence of glucose or glycerol had no
effect on 3-phosphoglyceric acid synthesis/accumulation, but it was completely utilized when forespores were incubated with
manganese plus ionophore (X 537A). No other metal(s) could substitute for manganese suggesting that manganese plays crucial
role in 3-phosphoglyceric acid metabolism 相似文献
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A. Westram J. R. Lloyd U. Roessner J. W. Riesmeier & J. Kossmann† 《Plant, cell & environment》2002,25(9):1133-1143
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High-performance liquid chromatography on a Zorbax NH2 analytical column, with acetonitrile: 0.05 m KH2PO4 (75:25, ) used as eluant, has allowed the separation, in less than 14 min, of ascorbic acid, erythorbic acid, dehydroascorbic acid, dehydroerythorbic acid, diketogulonic acid, and diketogluconic acid. Ultraviolet monitoring at 268 nm allows ascorbic acid and erythorbic acid to be detected at the 25-ng level, while refractive index detection monitors the elution of all six compounds. Tyrosine is a good internal standard, being well separated from the other compounds and having an adequate ultraviolet absorption at 268 nm. We have found dithiothreitol to be effective in rapidly reducing dehydroascorbic acid to ascorbic acid, providing the basis for indirectly determining dehydroascorbic acid after its reduction. The potential of this high-performance liquid chromatographic procedure for evaluating the levels of these compounds in orange juice and urine is demonstrated. 相似文献
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