Acetylpolyamine oxidase

In mammalian cells, the catabolism of spermine to spermidine occurs via one of two distinct pathways. As a substrate for spermidine/spermine IV -acetyltransferase (SSAT), spermine can be converted to A -acetylspermine, which is subsequently oxidized by the FAD-dependent acetylpolyamine oxidase (APAO) to form spermidine. Conversely, spermine can be directly oxidized by spermine oxidase (SMOX) to form spermidine. Spermidine is then back-converted to putrescine through the two-step SSAT/APAO reaction that includes an Af-acetylspermidine intermediate (Fig. 5.1). 

Fig. 5.1 The mammalian polyamine catabolic pathway. Spermine (Spm) is back-converted to spermidine (Spd) by either spermine oxidase SMOX) or spermidine/spermine Af-acetyltransferase SSAT) followed by acetylpolyamine oxidase APAO). Spermidine is further back-converted to putrescine Put) through the same SSAT/APAO mechanism. Both oxidation reactions generate the reactive oxygen species ROS) precursor H2O2 and aldehydes as by-products. The resulting reduction in spermine and spermidine pools implies diminished antioxidant and antiinflammatory functions...

Monoacetylpolyamines that are reabsorbed by the renal tubular system are converted to free polyamines by acetylpolyamine oxidase (APAO) and subsequently reutilized in the body. Importantly, DiAcSpm is not reabsorbed by this route. It is likely that the total amount of DiAcSpm excreted from cells is recovered in the urine without significant loss, whereas the amount of urinary monoacetylpolyamines decreases by an unknown amount compared to that originally excreted from the cells as a result of renal reabsorption and subsequent reutilization. 

Federico R, Angelini R (1991) Polyamine catabolism in plants. In Slocum RD, Flores HE (eds) Biochemistry and physiology of polyamines in plants. CRC, pp 41-56 Federico R, Ercohni L, Laurenzi M, Angelini R (1996) Oxidation of acetylpolyamines by maize polyamine oxidase. Phytochemistry 43 339-341... 

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