Abstract:
:The membrane potential and pH gradient over the plasma membrane of the protozoan parasite Trypanosoma brucei were measured with radioactive indicators in combination with the silicone oil centrifugation technique over a range of temperatures. At 37 degrees C a small membrane potential and pH gradient of similar magnitude, but of opposite polarity, were measured. The resulting electrochemical proton gradient was almost zero. However, when the temperature was lowered from 37 degrees C to 22 degrees C, the internal pH was kept constant independent of the external pH and a membrane potential of between -100 and -150 mV was measured, depending on the external pH. Measurements at various temperatures between 15 degrees C and 37 degrees C revealed that above 26 degrees C the membrane potential collapsed and that this collapse correlated with a sudden increase in membrane fluidity. The uptake of 2-deoxy-D-glucose and of pyruvate, which are both mediated by facilitated diffusion carriers in the plasma membrane of the trypanosome, were also affected by this sudden increase in fluidity of the membrane. The overall rate of the conversion of glucose into its metabolites, which is independent of the plasma membrane, varied only gradually. We conclude (i) that major changes occur in the plasma membrane of T. brucei around 26 degrees C, that affect all membrane related processes; (ii) that the electrochemical proton gradient plays a minor role in the energy metabolism of T. brucei when it resides in the bloodstream of the mammalian host at 37 degrees C; and (iii) that below 26 degrees C an electrochemical proton gradient is maintained over the plasma membrane.
journal_name
Mol Biochem Parasitoljournal_title
Molecular and biochemical parasitologyauthors
Ter Kuile BH,Wiemer EA,Michels PA,Opperdoes FRdoi
10.1016/0166-6851(92)90123-2subject
Has Abstractpub_date
1992-10-01 00:00:00pages
21-7issue
1-2eissn
0166-6851issn
1872-9428pii
0166-6851(92)90123-2journal_volume
55pub_type
杂志文章abstract::When the malarial parasite Plasmodium falciparum multiplies in erythrocytes it dramatically increases uptake of essential metabolic precursors (nucleosides, nucleobases and glucose) and export of lactic acid by undefined mechanisms. The first evidence is provided here, by a detailed study in Xenopus laevis oocytes, th...
journal_title:Molecular and biochemical parasitology
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pub_type: 杂志文章
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journal_title:Molecular and biochemical parasitology
pub_type: 杂志文章
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更新日期:1992-12-01 00:00:00
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更新日期:1992-12-01 00:00:00
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journal_title:Molecular and biochemical parasitology
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journal_title:Molecular and biochemical parasitology
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