Title: Notes: Formation of Large Thioredoxin f Accompanies Chloroplast Development in Scenedesmus obliquus
Abstract: Chloroplast-free mutant cells C-2A′ of the green algae Scenedesmus obliquus lack thioredoxin f, which functions in the light activation of chloroplast enzymes, but do contain the regular thioredoxins I and II. When dark-grown algae are transferred to light, thioredoxin f activity appears rapidly and increases in parallel with photosynthetic activities: however it precedes chlorophyll biosynthesis. The formation of thioredoxin f is inhibited by cydoheximide indicating that it occurs on the cytoplasmic ribosomes, in accord with the lack of thioredoxin genes on the chloroplast genomes.