Conversion of 5-aminoimidazole ribotide to the pyrimidine of thiamin in enterobacteria: study of the pathway with specifically labeled samples of riboside.
Samples of 5-amino-1-(beta-D-ribofuranosyl)imidazole labeled with 13C at position C-1 or C-2 of the ribose part or with 15N at position N-3 or amino of the imidazole part were prepared by chemical synthesis. The incorporation of label from these samples into the pyrimidine of thiamin biosynthesized by a mutant strain of Salmonella typhimurium was studied by GC-MS. The results show clearly that in enterobacteria the methyl carbon atom and the N-1 nitrogen atom of one molecule of thiamin pyrimidine derive from the same molecule of 5-aminoimidazole ribotide. More specifically, the methyl carbon atom comes from the carbon C-2' of the ribose part and the nitrogen N-1 from nitrogen N-3 of the imidazole; furthermore, the amino nitrogen of the aminoimidazole becomes the amino nitrogen of the pyrimidine.
Estramareix
B
B
Institut de Chimie Moléculaire d'Orsay, Laboratoire de Chimie Organique Multifonctionelle associé au CNRS, URA 462, Université de Paris-Sud, France.
David
S
S
D002247:Carbon Isotopes; D008401:Gas Chromatography-Mass Spectrometry; D007202:Indicators and Reagents; D009154:Mutation; D012265:Ribonucleotides / Q000138:chemical synthesis / Q000378:metabolism*; D012486:Salmonella typhimurium / Q000235:genetics / Q000378:metabolism*; D013831:Thiamine / Q000096:biosynthesis*
D002247:Carbon Isotopes; D007202:Indicators and Reagents; D012265:Ribonucleotides; C024828:aminoimidazole ribotide; D013831:Thiamine