An oxidase catalyzing conversion of N-alpha-benzyloxycarbonyl-L-lysine (N-alpha -Z-L-IySine) to N-alpha-benzyloxycarbonyl-L-aminoadipate-delta-semialdehyde (N-alpha-Z-L-AASA) was purified from Rhodococcus sp. AIU Z-35-1, and its properties were revealed. This enzyme catalyzed an oxidative deamination of the epsilon-amino group of N-alpha-aCyl-L-lysine and the alpha-amino group of N-epsilon-acyl-L-lysine. The apparent K-m value for N-alpha-acetyl-L-lysine was much larger than that for N-epsilon-acetyl-L-lysine. The peptidyl L-lysines, L-lysine and many other L-amino acids were also oxidized, but N-alpha-aCyl-D-lysine, N-alpha-acyl-D-lysine and D-amino acids were not. Thus, the conversion of N-alpha-Z-L-lysine into N-alpha-Z-L-AASA was catalyzed by the L-amino acid oxidase with broad substrate specificity. This enzyme, a flavoprotein with a molecular mass of 100 kDa, consisted of two identical subunits of 51 kDa.