MEMBRANE POTENTIAL AND MICROSECOND TO MILLISECOND DELAYED LIGHT EMISSION AFTER A SINGLE EXCITATION FLASH IN ISOLATED CHLOROPLASTS
- 2 January 1978
- journal article
- research article
- Published by Wiley in Photochemistry and Photobiology
- Vol. 27 (1) , 61-71
- https://doi.org/10.1111/j.1751-1097.1978.tb07566.x
Abstract
Abstract— The effect of light‐induced and salt‐jump induced membrane potential on microsecond and millisecond delayed light emission from chloroplasts, following a single 10 ns flash, have been studied. Microsecond delayed light emission is shown to be independent of the membrane potential contrary to proposals that the activation energy for delayed light emission can be modulated by transmembrane electric fields. This result is discussed in terms of the possible origin of this short‐lived emission. Millisecond delayed light after a single excitation flash is enhanced by membrane potential only if a proton gradient is present. By measuring changes in ms delayed light caused by simultaneous injection of KC1 and Na‐benzoate (which creates a proton gradient) in the presence of valinomycin, the light‐induced potential generated across the thylakoid membrane by a single excitation flash was calibrated and found to be 128 ± 10 mV in agreement with the recent measurements of Zickler and Witt (1976) based on voltage‐dependent ionophores. It is concluded that the secondary charges that give rise to ms delayed light, after a single flash, do not fully span the membrane.This publication has 42 references indexed in Scilit:
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