Abstract
cDNA encoding the sea hare-derived antitumour-antibacterial protein Aplysianin A (APA) was expressed on Escherichia coll. APA displays sequence similarity to L-amino acid oxidase (LAAO) found in the snake (Crotalus atrox) venom. Spectrophotometric analysis along with thin layer chromatography of APA indicated that one flavin adenine dinucleotide, a cofactor of LAAO, bound to each subunit of the homotetramer. APA also displayed LAAO activity. Specifically, treatment of L-phenylalanine with APA resulted in the generation of hydrogen peroxide. This finding indicated that the antibacterial activity of APA is mainly caused by hydrogen peroxide production.
