Tyrosine O-sulphate in Fibrinogen and Fibrin.

This paper describes the details of the identification and determination of tyrosine 0-sulphate in fibrinogen, fibrin and fibrinopeptide B, as already reported in preliminary communications by the author under his previous names (Bettelheim, 1954; Bettelheim-Jevons, 1958). The first indication of the presence of tyrosine in modified form came during work on the peptides liberated from bovine fibrinogen during clotting by thrombin (Bailey & Bettelheim, 1955; Bettelheim, 1956). One of these peptides, fibrinopeptide B, was found to give rise to tyrosine on acid hydrolysis; yet the peptide showed no trace of the absorption peaks at 275 and 293 m,u characteristic of tyrosine in neutral and alkaline solution respectively. Further, after dinitrophenylation of the peptide with 1fluoro-2,4-dinitrobenzene, acid hydrolysis gave rise to free tyrosine and not its 0-dinitrophenyl derivative. Some group, therefore, blocks the phenolic hydroxyl group of tyrosine in the intact peptide. This group was found to be readily removed by acid but not by alkali. Marked lability to acid and stability to alkali is characteristic of aryl sulphates, and the presence of tyrosine 0-sulphate was confirmed as described below. Further, development of a method for determining tyrosine 0-sulphate even in the presence of a large excess of tyrosine made it possible to show its presence also in fibrinogen and fibrin from various mammalian species. Tyrosine 0-sulphate is excreted in considerable amounts in human urine (Tallan, Bella, Stein & Moore, 1955). The incorporation of inorganic [35S]sulphate into the tyrosine 0-sulphate residue of fibrinopeptide B has been demonstrated (Blomback, Bostrom & Vestermark, 1960), and the metabolic fate of this residue has been studied (Jones, Dodgson, Powell & Rose, 1963).