Isolation and partial characterization of a P870 reaction center complex from wild type Rhodospirillum rubrum

P870 was isolated from wild type Rhodospirillum rubrum by solubilization with dodecyldimethylamine oxide followed by ammonium sulfate precipitation. The particle contains some carotenoids, 0.3 mole of ubiquinone per mole of P870 and no cytochrome. The apparent particle weight is 140 000. Electrophoresis in dissociating media containing 0.1% sodium dodecyl sulfate shows the existence of at least two and more likely three protein bands. The complex is calculated to have a minimal molecular weight of 70 600 ± 3200 and is supposed to be formed of three protomers.