INTERFERENCE OF EXCESS CO2 IN ASSAYS OF ARGININE AND ORNITHINE DECARBOXYLASES OF CYANOBACTERIA ANABAENA-FLOS-AQUAE IC-1

A release of CO2 not related to arginine and ornithine decarboxylase a ctivities was found in enzyme extracts of Anabaena flos-aquae IC-1, Th e CO2 released was higher than that due to arginine and ornithine deca rboxylase activities calculated from labeled agmatine and putrescine, respectively (about 35- to 40-fold in assays of crude extracts and sev en times in those of partially purified enzymes). L-Arginine and L-orn ithine were used not only by their respective decarboxylases, but also by other unidentified enzymes. Preliminary study suggests that the ex cess CO2 in the decarboxylase assays was possibly from L-amino acid ox idase activity, since addition of exogenous catalase to the assays inh ibited the release of CO2. Paper electrophoresis proved to be useful i n a separation of L-amino acid from the corresponding amine and is the refore recommended for the determination of released radioactive amine in the decarboxylase assays. In addition to agmatine and putrescine, two unidentified products were found on an electrophoretogram, suggest ing that other unidentified enzymes are also active towards L-amino ac id substrates. Assays of arginine and ornithine decarboxylases in plan ts, cyanobacteria, and possibly also green algae, should be based on t he production of radioactive amines rather than on the determination o f CO2 released.