Involved in the protection against polyamine toxicity by regulating their concentration. Catalyzes the transfer of an acetyl group from acetyl coenzyme A (AcCoA) to the primary amino groups of spermidine to yield N(1)- and N(8)-acetylspermidine. It can also use spermine. acetyl-CoA + an alkane-alpha,omega-diamine = an N-acetylalkane-alpha,omega-diamine + CoA + H(+) acetyl-CoA + spermidine = CoA + H(+) + N(1)-acetylspermidine acetyl-CoA + spermidine = CoA + H(+) + N(8)-acetylspermidine acetyl-CoA + spermine = CoA + H(+) + N(1)-acetylspermine Amine and polyamine degradation; spermidine degradation. Amine and polyamine degradation; spermine degradation. Homododecamer. Belongs to the acetyltransferase family.