Sites of Biosynthesis of Carotenoids in Capsicum Chromoplasts

Abstract

Capsicum chromoplasts incubated with isopentenyl diphosphate actively synthesize carotenoids. The enzymes involved in these reactions are compartmentalized; the stroma is the site of phytoene synthesis, the 1st colorless carotenoid, while desaturation and cyclization of the latter leading to colored carotenoids, occur in the membrane fraction (chromoplast envelope plus achlorophyll lamellae derived in part from the inner envelope membrane). Phytoene synthetase could be used as a marker of chromoplast stroma.