Correlation between Field Formation, Proton Translocation, and the Light Reactions in Photosynthesis

Abstract

Electrical field changes across the function membrane of photosynthesis have been measured via special absorption changes. These occur by the action of the field on pigments which are located within the membrane. - Proton translocation has been measured by absorption changes of added pH indicators. Repetitive flash technique has been used for the sensitive detection of these absorption changes. 1. Each of the two light reactions of photosynthesis sets on one half of the electrical field. 2. The action spectra indicate that the two light reactions which set on the field are identical with those which promote the electron transfer. 3. The voltage set on in the elementary act both light reactions is V₀=50 mV. 4. Each of the two light reactions translocates one proton across the membrane. 5. The proton uptake is faster than 8 · 10⁻³ sec. 6. Two protons are translocated per one electron transferred to a terminal acceptor. 7. A reaction scheme compatible with the measured correlation between the light reactions, electron transfer, field formation, and proton translocation is depicted in Fig. 7.