Measurement of Spermidine/Spermine N<sup>1</sup>-AcetyItransferase Activity

Abstract

The breakdown of the polyamines, spermidine and spermine (Fig. 1), is a two-step process involving in the first reaction, spermidine/spermine N 1-acetyltransferase (abbreviated to N 1-SAT or SSAT), and in the second reaction, polyamine oxidase (PAO). N 1-SAT is the rate-limiting enzyme in this catabolic pathway. It is a highly inducible enzyme whose activity is increased by a range of hormones and drugs (1–3) N 1-SAT acetylates primary amino groups separated from another nitrogen atom by a three-carbon aliphatic chain (4). The reaction appears to occur by an ordered Bi Bi mechanism. The enzyme acetylates both spermine and spermidine, but it is unclear which of these polyamines is the preferred substrate in vivo.