Studies on l-tyrosine O-sulphate. 3. The metabolic fate of the L-tyrosine O[35S]-sulphate residue of 35S-labelled rabbit fibrinopeptide B

Abstract

The bulk of the dose of intraperitoneally injected potassium L-tyrosine O[S35]-sulphate was rapidly eliminated by rabbits in an unchanged form in the urine. Small amounts of p-hydroxy-phenylacetic acid [S35]sulphate also appeared in the urine. Fibrinopeptide B containing a L-tyrosine O[S35]-sulphate residue was prepared from the fibrinogen of rabbits that had been injected with Na2 35SO4. Intravenous or intraperitoneal injection of the labelled fibrinopeptide into rabbits was followed by the appearance of the S35 in an ester-bound form in the urine. The behaviour on ion-exchange columns of this labelled urinary material showed that it was no longer associated with fibrinopeptide B. Two radioactive metabolites could be separated from the urine on Dowex 50 (H+ form) resin. The positions of emergence of these compounds from the column coincided approximately with those of free L-tyrosine O[S35]-sulphate and p-hydroxy-phenylacetic acid [S35]sulphate.