Biosynthesis of ergothioneine by Claviceps purpurea. 3. The incorporation of labelled histidine.

common to both these compounds (Heath & Wildy, 1956a, b). These results indicated that this fungus forms ergothioneine by methylation and sulphuration of histidine. Subsequent work (Wildy & Heath, 1956, 1957) revealed that [2(ring)-14C]histamine would not serve as a precursor of the imidazole nucleus of either histidine or ergothioneine. Various metabolites of histamine, imidazoles possessing modified side chains, also failed to provide the requirements of an ergothioneine precursor. In order to confirm that histidine was a direct precursor of ergothioneine, experiments were carried out with histidine labelled both in the side chain and the imidazole ring. A preliminary report of this work has already been published (Heath & Wildy, 1957).