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

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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.