Formation of Cyclic Adenosine-S'-S'-monophosphate (cAMP) from Adenosine-5'-phosphosulfate (APS) in Chlamydomonas reinhardtii

Levels of cyclic adenosine monophosphate (cAMP) have been determined in the green alga Chlamydomonas reinhardtii strain CW 15. In the early exponential growth no cAMP was detected, however, in the middle of the exponential growth phase 2.4 pmol cAMP/mg protein were found and the cAMP level increased to 18.8 pmol/mg protein in the stationary phase. An enzyme fraction has been isolated from Chlamydomonas, which produced cAMP in vitro using adenosine-5'-phosphosulfate (APS) as a substrate. This protein fraction was isolated by ammoniumsulfate precipitation, DEAE-cellulose chromatography and Sephadex-G-100 gel filtration. A solvent system was developed for thin layer chromatography to separate cAMP from APS, adenosine-5'-phosphoramidat (APN), 5'-AMP and adenosine. The product was identified as cAMP by cochromatography, coelectrophoresis, treatment with phosphodiesterase, chromato­ graphy on Biorad-columns and by the protein-binding assay. The so far purified protein fraction produced 151 pmol cAMP/mg protein and hour in vitro, using APS as a substrate.