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| Predicate | Object |
|---|---|
| rdf:type | |
| lifeskim:mentions | |
| pubmed:issue |
1
|
| pubmed:dateCreated |
1984-9-12
|
| pubmed:abstractText |
A fast-responding O2 electrode has been used to confirm and extend observations of a significant kinetic discrepancy between O2 reduction and consequent proton translocation in 'O2-pulse' experiments in intact cells of P. denitrificans. The permeant, chaotropic SCN- ion abolishes this discrepancy, and greatly increases the observable----H+/O ratio, to a value approaching its accepted, true, limiting stoichiometry. The observable H+ decay rates are very slow, particularly in the absence of SCN-. The submaximal----H+/O ratios observed in the absence of SCN- are essentially independent of the size of the O2 pulse, in a manner not easily explained by a delocalised chemiosmotic energy-coupling scheme. Osmotically active protoplasts of P. denitrificans do not show a significant kinetic discrepancy between O2 reduction and H+ translocation, even in the the absence of SCN-. However, the submaximal----H+/O ratios observed in the absence of SCN- are again essentially independent of the size of the O2 pulse. As in intact cells, the observable H+ decay rates are very slow. The energy-transfer inhibitor venturicidin causes a significant increase in the----H+/O ratio observed in protoplasts of P. denitrificans in the absence of SCN-; the decay kinetics of the H+ translocation process are also somewhat modified. Nevertheless, the----H+/O ratio observed in the presence of venturicidin is also independent of the size of the O2 pulse. This observation militates further against arguments in which (a) a non-ohmic leak of protons from the bulk aqueous phase might alone be the cause of the low----H+/O ratios observed in the absence of SCN-, and (b) in which there might be a delta p-dependent change ('redox slip') in the actual----H+/O ratio. It is concluded that the observable protonmotive activity of the respiratory chain of P. denitrificans in the absence of SCN- is directly influenced by the state of the H+-ATP synthetase in the cytoplasmic membrane of this organism. We are unable to explain the data in terms of a model in which the putative protonmotive force may be acting to affect the----H+/O ratio. The possibility is considered that the delocalised bulk-to-bulk phase membrane potential set up in response to protonmotive activity is energetically insignificant.
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| pubmed:language |
eng
|
| pubmed:journal | |
| pubmed:citationSubset |
IM
|
| pubmed:chemical | |
| pubmed:status |
MEDLINE
|
| pubmed:month |
Jul
|
| pubmed:issn |
0006-3002
|
| pubmed:author | |
| pubmed:issnType |
Print
|
| pubmed:day |
27
|
| pubmed:volume |
766
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| pubmed:owner |
NLM
|
| pubmed:authorsComplete |
Y
|
| pubmed:pagination |
222-32
|
| pubmed:dateRevised |
2006-11-15
|
| pubmed:meshHeading |
pubmed-meshheading:6743650-Cell Membrane,
pubmed-meshheading:6743650-Hydrogen-Ion Concentration,
pubmed-meshheading:6743650-Kinetics,
pubmed-meshheading:6743650-Lactones,
pubmed-meshheading:6743650-Oxygen Consumption,
pubmed-meshheading:6743650-Paracoccus denitrificans,
pubmed-meshheading:6743650-Thiocyanates,
pubmed-meshheading:6743650-Venturicidins
|
| pubmed:year |
1984
|
| pubmed:articleTitle |
On the effects of thiocyanate and venturicidin on respiration-driven proton translocation in Paracoccus denitrificans.
|
| pubmed:publicationType |
Journal Article,
Research Support, Non-U.S. Gov't
|