Effects of transition metals and of metal-binding antihypertensive agents on tryptamine oxidase and dopa decarboxylase

SummaryThe effects of transition and subgroup II metal ions on the activities of crude preparations of tryptamine oxidase and dopa decarboxylase, obtained from fresh guinea pig livers and kidneys, were assayed with the Warburg method. Tryptamine oxidation was accelerated by 10-6M vanadyl ion. Cobalt had a similar but less potent effect. Dopa decarboxylation was inhibited by 10-4M mercuric or cadminum ions. Moreover, 10-4M or lower concentrations of two clinically effective antihypertensive hydrazines also caused acceleration of tryptamine oxidation and inhibition of dopa decarboxylation.