真核生物, Saccharomyces cerevisiaeにおけるチアミン・ピリミジン部へのグリシンの取り込みの検討

概要

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The biosynthetic routes of the pyrimidine moiety of thiamin differ between eucaryotes and procaryotes. In eucaryotes, the N-3, C-4, and amino-N at C-4 of the pyrimidine have been shown to originate from N-1, C-2, and N-3 of imidazole ring of histidine, respectively. Further C-6, C-5 and C-7 of the pyrimidine are C-8 of the pyrimidine remains unsolved. In procaryotes, N, C-1 and C-2 of glycine are incorporated into N-1, C-4 and C-6 of the pyrimidine, respectively. We studied the incorporation of glycine into the pyrimidine in a eucaryote, Saccharomyces cerevisiae. The results rerealed that [1-^<14>C]glycine was not incorporated into the pyrimidine, whereas [2-^<14>C]glycine was incorporated with a little dilution. The incorporation of [2-^<14>C]glycine was diluted by the addition of formate. The localization of the radioactivity in the pyrimidine labeled with [2-^<14>C]glycine was at C-4 of the pyrimidine. It was concluded that C-2 of glycine was cleaved into one-carbon unit, which was then incorported into C-4 of the pyrimidine via C-2 of the imidazole of histidine; indicating that glycine was not directly incorporated into the pyrimidine as a molecule.
日本ビタミン学会の論文
1990-06-25