Light Modulation of Glyceraldehyde-3-phosphate Dehydrogenase and Glucose-6-phosphate Dehydrogenase by Photosynthetic Electron Flow in Pea Chloroplasts.

Light activation of NADP-linked glyceraldehyde-3-P dehydrogenase (EC 1.2.1.13) and light inactivation of glucose-6-P dehydrogenase (EC 1.1.1.49) appear to be modulated within pea leaf chloroplasts by mediators which are reduced by photosynthetic electron flow from the photosystem I reaction center. Dichlorophenyl-1, 1-dimethylurea inhibition of this modulation can be completely reversed by ascorbate plus 2,6-dichlorophenolindophenol in broken chloroplasts, but not in intact chloroplasts. Intact chloroplasts are impermeable to 2,6-dichlorophenolindophenol at pH 7.5. Studies on the effect of light in reconstituted chloroplasts with photosystem I-enriched particles in the place of whole thylakoids revealed that photosystem I participates in the light modulation of NADP-linked glyceraldehyde-3-P dehydrogenase and of glucose-6-P dehydrogenase.