The conjugation of tyramine with sulphate by liver and intestine of different animals

Abstract

Tyramine was conjugated with sulfate by extracts of monkey intestine and livers of monkey, rat, mouse, guinea pig and man. The activity measured in monkey intestine was almost 3 times that of monkey liver. Labeled tyramine sulfate synthesized from [14C]tyramine, [3H]tyramine or Na235SO4, on acid hydrolysis, released its radioactive precursor. Liver extracts of monkey, rat, mouse and guinea pig synthesized, respectively, 145, 66, 21 and 6 pmol of [14C]tyramine sulfate/min per mg of protein. Except with the monkey, intestine exhibited very low activity. trans-2-Phenylcyclopropylamine, a monoamine oxidase inhibitor, was added as a routine to the enzyme preparation, as its omission resulted in the production of p-hydroxyphenylacetic acid in appreciable amounts. This oxidative deamination of tyramine, however, did not decrease the sulfo-conjugation of tyramine. The low Km (9.1 .mu.M) of sulfotransferase for tyramine is probably responsible.