Properties of reaction center depleted membranes of Rhodospirillum rubrum

Intracytoplasmic membranes isolated from Rhodospirillum rubrum, mutant strain VI, were extracted with the detergent lauryl dimethyl amine oxide. Subsequently two fractions were isolated, one of which contained reaction centers and the other contained light-harvesting bacteriochlorophyll of the photosynthetic apparatus. The two fractions are compared with unextracted membranes on the basis of protein patterns obtained by different methods of polyacrylamide gelelectrophoresis. Electron micrographs of the light-harvesting bacteriochlorophyll fraction reveal the presence of vesicular membrane structures. The only difference between such membranes and unextracted membranes is identified after freeze etching. While unextracted membrane surfaces are studded with particles extracted membranes exhibit a smooth surface.