1-N-acetylspermidine in roots of maize seedlings

The presence of 1-N-acetylspermidine was revealed in root tissues of 2-d-old maize seedlings by inhibiting in vivo polyamine oxidase activity with acetylspermine added to the growth solution. The identity of 1-N-acetylspermidine was confirmed by HPLC-mass spectrometry. C-14-spermidine added to 1 mM spermidine in presence or absence of 1 mM acetylspermine did not lead to the synthesis of C-14-acetylspermidine. Results indicate that acetylspermidine is not involved in the spermidine-lo-putrescine interconversion pathway and exogenous spermidine cannot be the substrate for the acetylation process. It is suggested that acetylation occurs in a subcellular compartment not permeable to exogenous spermidine.