The enzyme generates the imine form of indole 3-pyruvate (IPA) from L-tryptophan (L-Trp), with concomitant two-electron reduction of O(2) to H(2)O(2). L-tryptophan + O2 = 2-iminio-3-(indol-3-yl)propanoate + H2O2 7-chloro-L-tryptophan + O2 = 3-(7-chloroindol-3-yl)-2-iminopropanoate + H2O2 Binds 1 FAD per subunit. Binds 1 Mg(2+) ion per subunit. Pigment biosynthesis; violacein biosynthesis. Homodimer. By N-acylhomoserine lactone (AHL). Violacein production is used as a biosensor for the detection of quorum-sensing AHL production. Violacein possesses antibacterial, antiviral, antimicrobial, antileishmanial, trypanocidal and potential antitumoral activities. Belongs to the flavin monoamine oxidase family.