[cAMP phosphodiesterase from phototrophic bacteria Rhodospirillum rubrum].

cAMP phosphodiesterase activity is discovered in supernatant of R. rubrum cell homogenate after centrifugation at 1000 g. The enzyme is highly active (5.62 nmoles/mg of protein per 1 min) at a broad pH range--from 7.0 to 9.0. The enzyme activity is strongly inhibited with caffeine and dithiotreitol and very significantly inhibited by ascorbic acid. The dependence of the enzyme activity on the incubation time and protein and substrate concentrations in the reaction mixture is estimated. cAMP phosphodiesterase is found in soluble fraction and in particule fractions sedimenting at 30 000 g. The enzyme activity is completely absent in washed chromatophores sedimenting at 160 000 g.