The involvement of lipids in light-induced charge separation in the reaction center of photosystem II

✍ Scribed by H. -J. Eckert; Y. Toyoshima; K. Akabori; G. C. Dismukes

• Publisher: Springer
• Year: 1987
• Tongue: English
• Weight: 587 KB
• Volume: 14
• Category: Article
• ISSN: 0166-8595
• DOI: 10.1007/bf00019590

✦ Synopsis

Extraction of PS II particles with 50 mM cholate and 1 M NaCl releases several proteins and lipids from the thylakoid membrane which are essential for 02 evolution, dichlorophenolindophenol (DCIP) reduction and for stable charge separation between P680 ÷ and QA. This work correlates the results on the loss of steady-state rates for 02 evolution and PS II mediated DCIP photo-reduction with flash absorption changes directly monitoring the reaction center charge separation at 830nm due to P680 ÷, the chlorophyll a donor. Reconstitution of the extracted lipids to the depleted membrane restores the ability to photo-oxidize P680 reversibly and to reduce DCIP, while stimulating 02 evolution minimally. Addition of the extracted proteins of masses 33-, 23-and 17-kDa produces no further stimulation of DCIP reduction in the presence of an exogenous donor like DPC, but does enhance this rate in the absence of exogenous donors while also stimulating 02 evolution. The proteins alone in the absence of lipids have little influence on charge separation in the reaction center. Thus lipids are essential for stable charge separation within the reaction center, involving formation of P680 + and QA.