BIOSYNTHESIS OF l-TYROSINE O-SULPHATE FROM THE METHYL AND ETHYL ESTERS OF l-TYROSINE

Abstract

Rat-liver supernatant preparations are capable of achieving the biological sulfation of L-tyrosine methyl ester, the reaction proceeding maximally at a substrate concentration of 30 mM and at pH 7.0. Two sulfated products are formed, one of which has been indenti-fied as L-tyrosine O-sulfate. On the basis of indirect evidence the other product can be assumed to be L-tyrosine O-sulfate methyl ester. An enzyme present in rat-liver supernatant preparations is capable of converting L-tyrosine O-sulfate methyl ester into L-tyrosine O-sulfate. This enzyme is inhibited by L-tyrosine methyl ester. L-Tyrosine ethyl ester also yields 2 sulfated products when used as an acceptor in the liver sulfating system. One of these has been identified chromatographically as L-tyrosine O-sulfate and the other may be presumed to be L-tyrosine O-sulfate ethyl ester.