Reconstitution of Photosynthetic Energy Conservation

Abstract

Photophosphorylation has been reconstituted in a liposomal system containing reaction centers of photosystem I and coupling‐factor complex, both highly purified from spinach chloroplasts. This energy‐converting model system was put together by diluting the preparation of the coupling‐factor complex with an aqueous suspension of proteolipid vesicles, preformed from photosystem‐I reaction centers and soybean phospholipids by sonication. In the presence of reduced N‐methylphenazonium methosulfate the system catalyzed photophosphorylation with rates up to 50 μmol ATP formed × mg chlorophyll⁻¹× h₋₁, which was sensitive to uncouplers and to N, N′‐dicyclohexylcarbodiimide. The properties of the system in comparison to chloroplasts is discussed.