Some properties of monoamine oxidase and a semicarbazide sensitive amine oxidase capable of the deamination of 5-hydroxytryptamine from porcine dental pulp.

The deamination of 5-hydroxytryptamine, tryptamine and benzylamine by porcine dental pulp membrane preparations is brought about not only by monoamine oxidase, but also by a clorgyline (and deprenyl) resistant), semicarbazide sensitive enzyme. The semicarbazide sensitive enzyme was also inhibited by aminoguanidine, hydroxylamine and phenylhydrazine, but was not affected to any significant extent by incubation at 50 degrees for up to 100 min. There was, on the other hand, considerable inhibition of monoamine oxidase activity after incubation at this temperature. The semicarbazide sensitive enzyme neither metabolised, nor was inhibited by putrescine or cadaverine. Mixed substrate experiments indicated that 5-hydroxytryptamine and tryptamine interacted at the same catalytic centre on the semicarbazide sensitive enzyme.