PathwayStep2525 PathwayStep2524 PathwayStep2526 PathwayStep2521 PathwayStep2520 PathwayStep2523 PathwayStep2522 Interconversion of polyamines Authored: Gopinathrao, G, 2008-05-21 17:26:32 Edited: Gopinathrao, G, 2006-04-27 13:13:48 GENE ONTOLOGYGO:0006596 Pubmed11564948 Pubmed12686127 Pubmed15221502 Pubmed15784477 Reactome Database ID Release 43351200 Reactome, http://www.reactome.org ReactomeREACT_14805 Reviewed: D'Eustachio, P, 2008-06-12 14:43:38 The reactions catalyzed by aminopropyl-transferases annotated above are generally irreversible. But spermine and spermidine can be recycled respectively into spermidine and putrescine. These events require the formation of N-acetylated intermediates, N1-acetylspermine and N1-acetylspermidine catalyzed by a cytosolic acetyl-CoA:spermidine/spermine N1-acetyl-tranferase (SSAT) enzyme.<br>Subsequently, polyamine-oxidase (PAO), a FAD enzyme present in the peroxysomes, yields a polyamine with release of an aldehyde (3-acetamindopropanal) and H2O2.<br>In addition, SMOX, a FAD-dependent, polyamine oxidase (PAOh1/SMO) that can efficiently use spermine as a substrate and is involved in interconversion reactions. N-acetylated spermidine (cytosol)=>N-acetylated spermidine (peroxisomal) Spermidine => N-acetylated spermidine N-acetylated spermine (cytosol)=>N-acetylated spermine (peroxisomal) N-acetylspermine is oxidised to spermidine Spermine is oxidized to spermidine N-acetylspermidine is oxidized to putrescine Spermine => N-acetylated spermine