Catabolism of tryptamine by cockroach head enzyme preparation

An enzyme preparation from the homogenate of American cockroach heads Periplaneta americana (L.)] converted tryptamine hydrochloride to a toluene-extractable material. Optimum conditions for the reaction were obtained with 0.3 M sodium phosphate buffer, pH 6.6, at 30°C. The enzyme was very unstable. Its activity was scarcely inhibited by such typical monoamine oxidase inhibitors as iproniazid phosphate and tranylcypromine hydrochloride. Enzyme activity was not affected by the addition of NADPH₂, but was accelerated by acetyl coenzyme A or coenzyme A. A main product of the enzymic reaction was isolated and identified as N-acetyltryptamine by chromatography and spectroscopic analyses, which suggests that the enzyme is a kind of N-acetyltransferase.