SULPHATE ESTER FORMATION FROM CATECHOLAMINE METABOLITES AND PYROGALLOL IN RAT BRAIN IN VIVO

—A sulphotransferase enzyme capable of utilizing ethanolic or glycolic catecholamine metabolites and other phenols as substrates was studied in rat brain in vivo following the intraventricular injection of sodium [³⁵S]sulphate and the subsequent isolation and identification of the labelled sulphate esters. A quantitative examination was made possible by the injection of increasing amounts of substrates of the enzyme together with sodium [³⁵S]sulphate and the application of Michaelis-Menten kinetics. 3-Methoxy-4-hydroxyphenylethyleneglycol and 3,4-dihydroxyphenylethyleneglycol were shown to be readily esterified as was 3-methoxy-4-hydroxyphenylethanol (‘half-saturating dose’ of 5-1, 34 and 18 nmol respectively). Three esters of pyrogallol were isolated after its administration. This compound was also shown to inhibit sulphate ester formation from both substituted glycols, probably by competitive inhibition. The amines 5-hydroxytryptamine and normetanephrine were not found to be substrates for the sulphotransferase system in brain.