Polyamine metabolism in Acanthamoeba culbertsoni.

1,3-Diaminopropane has been identified as the major polyamine of Acanthamoeba culbertsoni. N-acetylputrescine and spermidine were present in appreciable amounts and putrescine as well as N-acetylspermidine were also detected, but spermine was absent. Changes in polyamine levels were observed during the growth of amoebae. Ornithine decarboxylase activity was detected in cell-free extracts but there was very low activity of arginine and lysine decarboxylases. A potent polyamine oxidase was demonstrated which preferentially acted on N8-acetyl-spermidine as the substrate while N1-acetylspermidine was a poor substrate; free polyamines did not serve as a good substrate for this enzyme. Active uptake of polyamines by the amoebae was also demonstrated.