Observations on the biosynthesis of thiamine in yeast.
1. Methods are described for the isolation of radioactively pure thiamine from yeast and its degradation on a small scale to its cyclic components. 2. A degradation of the pyrimidine ring and a thin-layer method for the separation of thiamine, its derivatives and pyrimidine and thiazole residues are described. 3. [(14)C]Formate is more effectively incorporated into the pyrimidine residue than into the thiazole residue, whereas the reverse is true with l-[Me-(14)C]methionine. 4. Experiments with [Me-(14)C,(35)S]methionine demonstrate that methionine provides an intact unit for the biosynthesis of the thiazole ring. 5. [6-(14)C]Orotic acid is insignificantly incorporated into the pyrimidine residue of thiamine. 6. Experiments with [1-(14)C]- and [2-(14)C]-acetate indicate that it is incorporated as a unit into the thiazole residue, but that only C-2 is incorporated into the pyrimidine residue. 7. l-[U-(14)C]Alanine is also effectively incorporated into the thiazole residue. 8. These results are discussed in relation to possible pathways of biosynthesis of the two ring components of the thiamine molecule.
D000085:Acetates / Q000378:metabolism; D000409:Alanine / Q000378:metabolism; D002849:Chromatography, Gas; D005561:Formates / Q000378:metabolism; D066298:In Vitro Techniques; D008715:Methionine / Q000378:metabolism; D009963:Orotic Acid / Q000378:metabolism; D011743:Pyrimidines / Q000096:biosynthesis; D012440:Saccharomyces / Q000378:metabolism*; D013831:Thiamine / Q000096:biosynthesis*; D013844:Thiazoles / Q000096:biosynthesis
D000085:Acetates; D005561:Formates; D011743:Pyrimidines; D013844:Thiazoles; D009963:Orotic Acid; D008715:Methionine; D000409:Alanine; D013831:Thiamine