Studies on the Biosynthesis of Corrinoids and Porphyrinoids. I : The Labeling of Oxygen of Vitamin B_<12>

概要

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Recently the amide-oxygen has been suggested to participate in the formation of the corrin ring of vitamin B_<12>. To confirm this hypothesis, ^<17>O-labeled aminolevulinic acid (ALA) was prepared and administered to Propionibacterium shermanii. The isolated vitamin B_<12> showed only broad ^<17>O signals in the oxygen-17 nuclear magnetic resonance (^<17>O-NMR) spectrum. However, distinct isotope-shifted peaks were observed in the ^<13>C-NMR spectrum of vitamin B_<12> isolated after incorporation of [1-^<13>C : 1,4-^<18>O_2]ALA. Of these shifted peaks, one peak (C_<27>) showed very low intensity. This indicates that dilution of ^<18>O occurred at the acetyl chain of the A ring of vitamin B_<12>. This result supports the assumption that the lactone formation of the A ring promotes the ring contraction, as proposed by Eschenmoser.
社団法人日本薬学会の論文
1989-05-25