The oxidation of tryptamine to 3-indolylacetaldehyde by plant amine oxidase

Publisher Website
Google Scholar
Abstract
Plant amine oxidase catalyzes the oxidation of tryptamine to 3-indolylacetaldehyde (IAc). This was established by the isolation of the 2:4-dinitrophenylhydrazone and dimedone derivatives of IAc from the reaction mixtures. The oxidation of 5-hydroxytryptamine is also catalyzed by the enzyme. A method is described for the estimation of IAc based on its oxidation, with silver oxide, to 3-indolylacetic acid (IAA). The IAA so formed is estimated with Salkowski reagent. With this method the effect of pH, substrate concentration, and reaction time on the yield of IAc was investigated. The enzyme was rapidly inactivated at high tryptamine concentrations. With low tryptamine concentrations and short reaction times (15 min.) yields of IAc of up to 90% of theoretical were obtained at pH 7-8. The yield decreased with increase in reaction time, particularly with alkaline reaction mixtures. This was probably due, in part at least, to polymerization of the IAc. It is suggested that the reaction forms a useful method of obtaining IAc. Two of the secondary reactions which occur when crude preparations of the amine oxidase are used to catalyze the reaction were identified as peroxidase-catalyzed oxidations of tryptamine and lAc.