[Structural organization of membranes reconstituted from phospholipids and subchromatophore pigment-protein...

Pigment--protein complexes of the P870 reaction centers and complexes of the bacteriochlorophyll light-harvesting antenna were isolated from the chromatophores of the non-sulfur purple bacterium Rhodospirillum rubrum by solubilization with detergents. The proteoliposomes containing the reaction centers or reaction centers and the light-harvesting antenna as well as liposomes formed from phospholipids were obtained by a self-assembly procedure using seya bean phospholipids. The freeze-fracture study showed that the proteoliposomes contain a large amount of globular particles. The particles incorporated into the two types of the proteoliposomes were distinguished in size. The globules of the reaction center and antenna complexes were bigger in size than the reaction center globules. The globular structures were not found in the liposomal membranes. The liposomes formed in the absence of the pigment--protein complexes were predominantly the multilamellar vesicles. The proteoliposomes were mostly represented as monolamellar membrane vesicles. The spatial arrangement of the reaction center complexes in the membranes is discussed.