Acetylates both spermidine and spermine at primary propyl amine moieties, with spermine being the preferred substrate. acetyl-CoA + an alkane-alpha,omega-diamine = an N-acetylalkane-alpha,omega-diamine + CoA + H(+) acetyl-CoA + spermine = CoA + H(+) + N(1)-acetylspermine acetyl-CoA + spermidine = CoA + H(+) + N(1)-acetylspermidine Putrescine and N(8)-acetylspermidine are competitive inhibitors of spermidine acetylation. Amine and polyamine degradation; spermine degradation. Amine and polyamine degradation; spermidine degradation. Belongs to the acetyltransferase family.