Membranes of Rhodospirillum rubrum: isolation and physicochemical properties of membranes from aerobically grown cells

M L Collins, R A Niederman
1976 Journal of Bacteriology  
Highly purified preparations of cytoplasmic and outer membrane were isolated from aerobically grown Rhodospirillum rubrum lysed by sequential treatment with lysozyme, ethylenediaminetetraacetate, and Brij 58. The membranes were resolved and separated from other cellular constituents by a combination of velocity and isopyknic sedimentation in sucrose density gradients. On the basis of their appearance in electron micrographs and their protein profiles in sodium dodecyl sulfate-polyacrylamide gel
more » ... -polyacrylamide gel electrophoresis, these preparations appear to be quite similar to those obtained from other gram-negative bacteria. The cytoplasmic membrane fraction contained the majority of the total membranebound succinic dehydrogenase activity and was 10-fold enriched in b-and c-type cytochromes with respect to the outer membrane. The latter fraction was characterized by a much greater carbohydrate content and the presence of arachidic acid, which is typical ofR. rubrum lipopolysaccharide. Their protein, fatty acid, and overall chemical compositions suggested that these preparations were freer from cross-contamination than those obtained from R. rubrum with currently available methods. 1316 on May 4, 2020 by guest
doi:10.1128/jb.126.3.1316-1325.1976 fatcat:bcxkrk3davgx3mx22xoopgcgya