Studies of the induction of spermidine/spermine N¹-acetyltransferase using a specific antiserum

A specific antiserum to rat liver spermidine/spermine N¹-acetyltransferase was used to study the induction of this protein. The antiserum had no effect on the spermidine acetylating capacity of crude nuclear extracts and very little effect on the activity present in crude cytosolic extracts from control rat tissues indicating that most of this activity is not due to spermidine/spermine N¹-acetyltransferase. Treatment of rats with carbon tetrachloride, spermidine, thioacetamide, or methylglyoxal bis(guanylhydrazone) produced a substantial increase in the spermidine acetylating capacity of rat liver cytosolic extracts which was exclusively due to an increase in the immunoprecipitable spermidine/spermine N¹-acetyltransferase protein. Exact measurement of the extent of this increase was not possible because the basal amount was too low to determine precisely but the amount of this enzyme increased about 250-fold with 6 h of treatment with carbon tetrachloride, about 25-fold at 6 h after spermidine, about 23-fold at 24 h after thioacetamide and up to 300-fold at 24 h after methylglyoxalbis(guanylhydrazone). Treatment of rats with spermidine also increased spermidine/spermine N¹-acetyltransferase in other tissues including lung, kidney and pancreas. The spermidine/spermine N¹-acetyltransferase protein was found to turn over very rapidly with a half-life of about 15 min in thioacetamide-treated rats and 180 min after carbon tetrachloride.