Hog kidney diamine oxidase (DAO) interacted with 1,3-diaminopropane, putrescine and cadaverine to arrest proliferation of cultured mammalian cells. The byproducts of DAO-substrate interaction, H2O2 and NH4+ are themselves cytotoxic but were apparently not responsible for any significant antiproliferative effect in the experimental system. DAO is known to react with putrescine to generate labile 4-aminobutyraldehyde. This primary product was compatible with a compound (radio-labelled) separated from DAO-putrescine reactive mixtures by ion-exchange chromatography. Its rate of generation, level attained and lability (half-life, 2 hr) in culture simulated conditions were measured. Circumstantial evidence suggested that the amine aldehyde products of diamine oxidation had a potent antiproliferative effect on cells.
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