S-Adenosylmethioninamine is a substrate that is required for the biosynthesis of polyamines including spermidine, spermine, and thermospermine. It is produced by decarboxylation of S-adenosyl methionine.
This reaction is catalyzed by S-adenosylmethionine decarboxylase. The enzyme binds to S-adenosyl methionine (SAM) and removes the carboxyl group from the methionine. Once formed, S-adenosylmethioninamine donates its aminopropyl group to synthesize polyamines. Polyamines are important for DNA stability, RNA function, and cell growth.