ABSTRACTThe effect of biogenic polyamines (agmatine, cadaverine, putrescine, spermidine, and spermine) on the activity of pork muscle aminopeptidase and alanyl aminopeptidase was investigated. Agmatine (5 mM) showed a powerful inhibitory effect for both enzymes (more than 50% inhibition). Cadaverine and less intensely putrescine showed similar inhibitory effects for both enzymes. All assayed polyamines inhibited activity of both aminopeptidases except spermine and spermidine which did not affect aminopeptidase B. Thus, one of these inhibitors could be used to avoid the interference of alanyl aminopeptidase when assaying aminopeptidase B in muscle extracts.