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The Relation between Photophosphorylation and Delayed Light Emission in Chloroplasts
Plant Physiology
|June 1, 1973
Summary
Delayed light emission in lettuce chloroplasts indicates proton motive force. Higher proton motive force correlated with increased delayed light emission, while phosphorylation decreased it.
Area of Science:
- Photosynthesis research
- Chloroplast bioenergetics
- Plant physiology
Background:
- Delayed light emission (DLE) is a phenomenon in photosynthesis.
- Understanding DLE provides insights into energy transduction within chloroplasts.
Purpose of the Study:
- To investigate the relationship between delayed light emission and proton motive force in isolated chloroplasts.
- To determine how factors like electron acceptors and phosphorylation affect DLE.
Main Methods:
- Studied 1-millisecond delayed light emission in isolated coupled lettuce chloroplasts.
- Manipulated proton motive force using ferricyanide, electron donors, ionophores, and salts.
- Assessed the impact of phosphorylation on DLE signals.
Main Results:
- DLE increased with ferricyanide or TMPD addition.
- ADP, ATP, DI0-9, phlorizin, NaCl, and high NaCl/NH4Cl increased DLE signal.
- Gramicidin, valinomycin, and low NaCl/NH4Cl decreased DLE.
- Phosphorylation significantly decreased DLE.
Conclusions:
- Delayed light emission magnitude directly reflects the proton motive force across the thylakoid membrane.
- Established a correlation between DLE and the electrochemical potential gradient for protons (H+).
- Quantified proton motive force changes during phosphorylation.
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