Abstract
Chloroplast ATP synthase is the well-studied thiol enzyme, which is reduced and activated by the chloroplast thioredoxin. Under the light, thioredoxin is reduced by the electrons from the photosynthetic electron transfer system via ferredoxin-thioredoxin reductase, and the reduced form thioredoxin attacks the disulfide bond on the γ subunit of the ATP synthase thus giving the active enzyme. However, not much is known on the redox state of this γ subunit in the intact chloroplasts nor the green leaves so far. There is only the report on the change of the redox state of the γ subunit, which was estimated from the fluorescence change of the chloroplasts itself.
In this study, we intended to directly determine the redox state of the γ subunit in vivo. To this end, we applied the combined methods using thiol specific modification and SDS-PAGE. The physiological significance of redox regulation of ATP synthase is discussed.
