The protein patterns of intracytoplasmic membranes and reaction center particles isolated fromRhodopseudomonas capsulata

Intracytoplasmic membranes of wild type strain 37 b 4 and mutant strains A1a car^-bchl^-, A1a car^-bchl⁺ ofRhodopseudomonas capsulata were isolated. The membrane proteins were solubilized and separated by polyacrylamide gel electrophoresis (methods of Takayamaet al., 1964; Weber and Osborn, 1969). The band patterns were compared with each other. From the strain A1a car^-bchl⁺ reaction center particles were isolated by treatment of membrane with Triton X-100 followed by sucrose density gradient centrifugation. The reaction center particles were found to be enriched in reaction center bacteriochlorophyll. This pigment shows a reversible bleaching at 855 nm and a blue shift at 798 nm. The light harvesting bacteriochlorophyll portion of this fraction was 14–22% of the total bacteriochlorophyll content. The three main proteins of the reaction center particles amount to about 80% of the total protein of the particles. The molecular weights of the main proteins were estimated to be 32000, 27500 and 22500 daltons.