S-adenosylmethionine decarboxylase proenzyme <p>Members of this protein family are the single chain precursor of the two chains of the mature S-adenosylmethionine decarboxylase as found in <taxon tax_id="2190">Methanocaldococcus jannaschii</taxon> (Methanococcus jannaschii), <taxon tax_id="1423">Bacillus subtilis</taxon> and a wide range of other species [<cite idref="PUB00044723"/>]. S-adenosylmethionine decarboxylase catalyses the decarboxylation of S-adenosylmethionine to provide the aminopropyl moiety required for spermidine biosynthesis from putrescine.</p>