The succinic dehydrogenase from Rhodospirillum rubrum.

Succinic dehydrogenase has usually been associated with a macromolecular intracellular unit (mitochondria) whenever the enzyme has been isolated. In an ultracentrifugal analysis of the composition of extracts of various organisms, Schachman et al. (1952) found that Rhodospirillum rubrum yielded particles with a wide range of sedimentation constants. Succinic dehydrogenase has been demonstrated in extracts of R. rubrum by Vernon and Kamen (1953) using the reduction of cytochrome c or a dye as the assay, and by Eisenberg (1953) with a manometric assay. This article describes the properties of a partially purified succinic dehydrogenase system from R. rubrum that is associated with particles that have the same sedimentation constants as do the particles bearing pigments. A soluble bacterial succinic dehydrogenase has been obtained from Azotobacter vinelandii (Repaske, 1954).