title: Precursors of the pyrimidine moiety of thiamine.
abstract: 1. A method was devised for obtaining the pyrimidine moiety of thiamine in a pure form after its excretion into the medium by de-repressed washed-cell suspensions of mutants of Salmonella typhimurium LT2. 2. By using amino acid-requiring mutants, this excretion of pyrimidine moiety was shown to be dependent on the presence of both methionine and glycine. 3. In the presence of either [Me-(14)C]methionine or [G-(14)C]methionine, methionine-requiring mutants did not incorporate radioactivity into the pyrimidine moiety. 4. In contrast, both [1-(14)C]glycine and [2-(14)C]glycine were incorporated into the pyrimidine moiety excreted by glycine-requiring mutants, and this occurred with little or no dilution of specific radioactivity. 5. The possible requirement for methionine as a cofactor and the significance of the incorporation of both carbon atoms of glycine are discussed.
mesh_terms: D000596:Amino Acids / Q000378:metabolism; D002247:Carbon Isotopes; D003864:Depression, Chemical; D004794:Enzyme Repression; D005001:Ethionine / Q000494:pharmacology; D005827:Genetics, Microbial; D005998:Glycine / Q000378:metabolism; D008715:Methionine / Q000378:metabolism; D008722:Methods; D009154:Mutation; D011743:Pyrimidines / Q000096:biosynthesis* / Q000302:isolation & purification; D011865:Radioisotope Dilution Technique; D012486:Salmonella typhimurium / Q000201:enzymology / Q000254:growth & development / Q000378:metabolism*; D013831:Thiamine / Q000096:biosynthesis*
chemical_list: D000596:Amino Acids; D002247:Carbon Isotopes; D011743:Pyrimidines; D008715:Methionine; D005998:Glycine; D005001:Ethionine; D013831:Thiamine