sentences:  Enzymatic evidence then showed that the three molecules of cadaverine are transformed to the quinolizidine ring via enzyme bound intermediates, without the generation of any free intermediates.Originally, it was thought that conversion of cadaverine to the corresponding aldehyde, 5-aminopentanal, was catalyzed by the enzyme diamine oxidase.The aldehyde then spontaneously converts to the corresponding Schiff base, Δ1-piperideine.