Abstract
Abstract The steady state extent of H+ uptake in illuminated chloroplasts can be observed routinely to be decreased by ADP in the presence of arsenate when these reagents are present at saturating concentrations. The failure of previous investigators to observe this phenomenon may be explained by the fact that suboptimal concentrations of ADP and especially arsenate were used. ATP (or ADP) in the absence of arsenate enhance the magnitude of the light-induced H+ concentration gradient in chloroplasts (ΔpH) by 0.15 to 0.2 unit. In the presence of arsenate, ΔpH was decreased by ADP up to 0.4 unit and this decrease was prevented by phlorizin, an energy transfer inhibitor. When phosphorylation and ΔpH, assayed under similar conditions, were varied either by decreasing light intensity or by adding an uncoupler, it was apparent that initial phosphorylation rates decreased much more rapidly than ΔpH. Plots of log phosphorylation rate against ΔpH were linear and showed that a decrease in ΔpH of 0.3 to 0.34 unit was accompained by a 10-fold decrease in the rate of phosphorylation. The observed, relatively small, decrease in ΔpH by phosphorylation is consistent with the apparent dependence of phosphorylation rate on ΔpH.
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Claims 6
Claim · model-written summary
Saturating ADP with arsenate decreased steady-state H+ uptake in illuminated chloroplasts.
- Treatment
- ADP in the presence of arsenatee0
- Outcome
- H+ uptakee0
- Direction
- decreasede0
- Qualifier
- saturating concentrationse0
Not reportedTaxonComparator
Verbatim
e0“The steady state extent of H+ uptake in illuminated chloroplasts can be observed routinely to be decreased by ADP in the presence of arsenate when these reagents are present at saturating concentrations.”
Claim · model-written summary
ATP or ADP without arsenate enhanced the light-induced chloroplast H+ gradient by 0.15 to 0.2 unit.
- Treatment
- ATP (or ADP) in the absence of arsenatee0
- Outcome
- light-induced H+ concentration gradiente0
- Direction
- enhancee0
- Value
- 0.15 to 0.2 unite0
Not reportedTaxonComparator
Verbatim
e0“ATP (or ADP) in the absence of arsenate enhance the magnitude of the light-induced H+ concentration gradient in chloroplasts (ΔpH) by 0.15 to 0.2 unit.”
Claim · model-written summary
ADP with arsenate decreased ΔpH by up to 0.4 unit.
Not reportedTaxonComparator
Verbatim
e0“In the presence of arsenate, ΔpH was decreased by ADP up to 0.4 unit and this decrease was prevented by phlorizin, an energy transfer inhibitor.”
Claim · model-written summary
Phlorizin prevented the ADP-associated ΔpH decrease.
Not reportedTaxonComparator
Verbatim
e0“In the presence of arsenate, ΔpH was decreased by ADP up to 0.4 unit and this decrease was prevented by phlorizin, an energy transfer inhibitor.”
Claim · model-written summary
With reduced light intensity or added uncoupler, phosphorylation rates fell faster than ΔpH.
- Treatment
- decreasing light intensity or by adding an uncouplere0
- Outcome
- initial phosphorylation ratese0
- Direction
- decreased much more rapidly than ΔpHe0
Not reportedTaxon
Verbatim
e0“When phosphorylation and ΔpH, assayed under similar conditions, were varied either by decreasing light intensity or by adding an uncoupler, it was apparent that initial phosphorylation rates decreased much more rapidly than ΔpH.”
Claim · model-written summary
A 0.3 to 0.34 unit decrease in ΔpH accompanied a 10-fold decrease in phosphorylation rate.
- Outcome
- rate of phosphorylatione0
- Direction
- decreasee0
- Value
- 10-folde0
- Qualifier
- 0.3 to 0.34 unite0
- Comparator
- ΔpHe0
Not reportedTaxon
Verbatim
e0“Plots of log phosphorylation rate against ΔpH were linear and showed that a decrease in ΔpH of 0.3 to 0.34 unit was accompained by a 10-fold decrease in the rate of phosphorylation.”