P-54 コリン、ポルフィリン類の生合成(ポスター発表の部)

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Biosynthesis of corrinoids and porphyrinoids were studied in Propionibacterium shermanii and Arthrobacter hyalinus. Feeding experiment of [1-^<13>C, 1,1,4-^<18> O_3]δ-aminolevulinic acid (ALA) into P. shermanii afforded^<13>C- and ^<18>O-labeled vitamin B_<12>. The ^<13>C-NMR spectrum showed that the all amide carbonyl signals were observed upfield ^<18>O-isotope shift. However, the shifted amide carbonyl signal at C-27 showed very low intensity. This indicates that the regioselective exchange of the carbonyl oxygen occurred at the acetyl chain of the A ring of vitamin B_<12>. This result supports the assumption that the δ-lactone formation of the A ring promotes the ring contraction. The biosynthetic origin of carbonyl oxygen of uroporphyrinogen III was investigated. [1-^<13>C, 1,1,4-^<18>O_3]ALA was fed to A. hyalinus, and the resulting porphyrin was esterified with trimethyloxonium tetrafluoroborate to afford ^<13>C-and ^<18>O-labeled uroporphyrin III octamethyl ester. The ^<13>C-NMR signals exhibited carbonyl carbon ^<18>O-isotope shifts of 4.9-5.1 Hz corresponding to doubly ^<18>O-labeled. Thus, the carbonyl oxygens of uroporphyrinogen III and its oxidized product uroporphyrin III originated from ALA. Those results show that the loss of ^<80>O at the acetate carbonyls of the A-ring in vitamin B_<12> docs not occur before the formation of uroporphyrinogen III. Factor II, III was isolated from P. shermanii after oxidation and esterification of precorrin-2, 3 which is the precursor of cobyrinic acid. Enzymatic formation of uroporphyrin was accomplished by using crude enzyme system prepared from A. hyalinus. The major product was uroporphyrin III.
天然有機化合物討論会の論文
1994-09-20

P-54 コリン、ポルフィリン類の生合成(ポスター発表の部)

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