<prompt> 1st product of tryptophan catabolism iskynurenineBradykininPAFXantheurenate  <response>: Tryptophan is an aromatic essential amino acid The major metabolic fate of tryptophan is to be oxidized by tryptophan pyrrolase tryptophan di-oxygenase It is a hemoprotein. The enzyme is inducible by coicosteroids. 