S-adenosylmethionine decarbo, Xenopus/Amphibian,ylase proenzyme (SAMDC) Adenosylmethionine decarbo, Xenopus/Amphibian,ylase (AdoMetDC) is a pyruvoyl-dependent enzyme that catalyzes the formation of the aminopropyl group donor in the biosynthesis of the polyamines spermidine and spermine. The enzyme is synthesized as a protein precursor and is activated by an autocatalytic serinolysis reaction that creates the pyruvoyl group. Both proenzyme processing and catalytic activity are stimulated by putrescine. Catalytic activity is inhibited by iodoacetic acid.