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1.
Roxanne Deslauriers Irena Ekiel Thérèse Kroft Ian C.P. Smith 《Biochimica et Biophysica Acta (BBA)/Molecular Cell Research》1982,721(4):449-457
High resolution 31P-NMR has been used for the non-invasive observation of metabolites and metabolic rates in blood of normal mice and of mice infected with Plasmodium berghei, the causative agent of malaria. 31P-NMR was used to quantitate levels of 2,3-diphosphoglycerate in whole cells as a function of the degree of parasitemia and yielded good agreement with the results of enzymatic assays. The time-dependence of 31P metabolites was monitored in both normal and infected erythrocytes, greater rates of decay of 2,3-diphosphoglycerate being observed in malarial blood which correlate with the level of parasitemia. Very high metabolic rates of infected cells render measurement of intracellular pH unreliable on freshly drawn whole blood. When appropriate measures are taken to avoid this complication, no difference is observed in the intracellular pH of parasitized and non-parasitized erythrocytes from infected animals. In both normal and parasitized mice the intraerythrocytic pH is more acidic than that of the suspending medium by 0.15 pH unit at 25°C. Unlike free-living protozoa, the parasitic protozoan Plasmodium does not contain detectable levels of phosphonates or polyphosphates, in either whole cells or perchloric acid extracts thereof. 相似文献
2.
Sub Sunoo Katsumi Asano Fumiyuki Mitsumori 《European journal of applied physiology and occupational physiology》1996,74(4):305-310
We measured ATP, phosphocreatine (PCr), inorganic phosphate (Pi), and the intracellular pH in rat hindlimb muscles during submaximal isometric exercise with various O2 deliveries using31P nuclear magnetic resonance spectroscopy (31P NMR) to evaluate changes in energy metabolism in relation to O2 availability. Delivery of O2 to muscles was altered by controlling the fractional concentration of inspired oxygen (F
IO2) at 0.50, 0.28, 0.21, 0.11 and 0.08 with monitoring partial pressure of oxygen and carbon dioxide, and bicarbonate at the femoral artery. The steady-state ratio of PCr : (PCr + Pi) during exercise decreased as a function ofF
IO2 even at 0.21. Significant acidification of the intracellular pH during exercise occurred at 0.08F
IO2. Change in the PCr : (PCr + Pi) ratio demonstrated that the oxidative capacity, i.e. the maximal rate of the oxidative phosphorylation reaction, in muscle was not limited by O2 delivery at 0.50F
IO2, but was significantly limited at 0.21F
IO2 or below. Change in the intracellular pH at 0.08F
IO2 could be interpreted as an increase in lactate, suggesting activation of glycolysis. Correlation between the PCr : (PCr + Pi) ratio and the intracellular pH revealed the existence of a critical PCr : (PCr + Pi) ratio and pH for glycolysis activation at around 0.4 and 6.7, respectively. 相似文献
3.
Observations on the phosphate status and intracellular pH of intact cells, protoplasts and chloroplasts from photosynthetic tissue using phosphorus-31 nuclear magnetic resonance. 总被引:8,自引:0,他引:8 下载免费PDF全文
Individual pools of intracellular inorganic phosphate (Pi) can be observed in the dark in intact cells, protoplasts and chloroplasts from photosynthetic tissue by using 31P nuclear magnetic resonance (n.m.r.). Estimates for the pH of vacuolar and extravacuolar compartments are reported although it is shown that intracellular pH is determined by the pH of the suspending medium. Mannose treatment of asparagus (Asparagus officinalis) cells and spinach (Spinacia oleracea) protoplasts results in the inhibition of photosynthesis. The mechanism of mannose phosphate sequestration of free Pi is supported by the 31P n.m.r. spectra of mannose-treated tissue. There is a fundamental difference in 31 P n.m.r. spectra of mannose-treated spinach protoplasts and asparagus cells, reflecting a difference in the availability of vacuolar Pi for cellular metabolism in these species. The 31P n.m.r. spectrum of intact spinach chloroplasts is reported. 相似文献
4.
Abstract Natural abundance 13 C NMR spectroscopy has identified sucrose and trehalose as the principle compatible solutes accumulated by non-halophilic purple and green sulphur bacteria respectively, in response to osmotic stress. Synthesis of glycine betaine as a compatible solute was rare in non-halophilic phototrophic sulphur bacteria and appears to be limited almost exclusively to halotolerant isolates, although all isolates tested were able to accumulate exogenous glycine betaine from the growth medium in response to osmotic stress. These data support the hypothesis that the degree of halotolerance of a microorganism may be due, at least in part, to the metabolic effects of the compatible solute(s) accumulated. 相似文献