The photosynthetic apparatus of Acetabularia mediterranea grown under red or blue light. Biophysical quantification and characterization of photosystem II and its core components

摘要: — The photosynthetic activity of white light-grown Acetabularia mediterranea Lamouroux (=A. acetabulum (L.) Silva) decreases under continuous red light to less than 20% within 3 weeks. Subsequent blue reactivates photosynthesis a relatively short period days. In former publication (Wennicke and Schmid, Plant Physiol.84,1252–1256, 1987) we have shown that the regulated rate limiting step, which is an immediate driven reaction, part photosystem II (PS II). following biophysical properties PS were analyzed in thylakoids isolated from algae grown weeks either or with without subsequent days illumination: (a) fluorescence induction time domain dominated by QA reduction, (b) slow decline reflecting pheophytin photoaccumulation, (c) absorption changes at 320 830 nm repetitive flash excitation as indicator for turnover P680, respectively, (d) oscillation pattern oxygen yield train dark adapted samples (e) binding capacity atrazine. None these functions severely affected, but minor impairment of20–30% was observed irradiation. do not fully account drastic reduction electron transport through 80% after treatment. Therefore, rate-limiting step appears be mainly located core complex itself. It seems likely regulation process predominantly comprises antenna system.