<prompt> Polyamine Ike putrescine is derived fromArginineOrnithineYohimibineArginosuccine  <response>: The enzyme ornithine decarboxylase ODC catalyzes the decarboxylation of ornithine a product of the urea cycle to form putrescine. This reaction is the committed step in polyamine synthesis. In humans, this protein has 461 amino acids and forms a homodimer.Ref: 