Ribulose-1,5-bis-Phosphate Carboxylase/Oxygenase Degradation in Isolated Pea Chloroplasts Incubated in the Light or in the Dark

Intact pea (Pisum sativum L.) chloroplasts isolated mechanically were incubated in the dark or in the light. After incubation intact chloroplasts were reisolated on Percoll steps prior to analysis. A 37 kD polypeptide derived from the large subunit of ribulose-1,5-bis-phosphate carboxylase/oxygenase accumulated during incubation in darkness. Other degradation products (45, 42, 37, and 32 kD) were detected on immunoblots from organelles incubated in the light. The catabolism of Rubisco in the chloroplasts was affected by the composition of the incubation medium.