TAILIEUCHUNG - Báo cáo khoa học: Mechanism of the ring contraction process in vitamin B12 biosynthesis by the anaerobe Propionibacterium shermanii under aerobic conditions

The mechanism of the ring contraction process during vitamin B12 biosyn-thesis by the anaerobe Propionibacterium shermaniiwas investigated under both aerobic and anaerobic conditions by means of feeding experiments withd-amino[1-13 C]levulinic acid (a biosynthetic intermediate of tetra-pyrrole) and d-amino[1-13 C,1,1,4-18 O3]levulinic acid in combination with 13 C-NMR spectroscopy. | ỊFEBS Journal Mechanism of the ring contraction process in vitamin B12 biosynthesis by the anaerobe Propionibacterium shermanii under aerobic conditions Katsumi lida Kuniaki Ohtaka and Masahiro Kajiwara Department of MedicinalChemistry Meiji PharmaceuticalUniversity Tokyo Japan Keywords biosynthesis 13C-NMR 8-amino 1-13C 1 1 4-18O3 levulinic acid Propionibacterium shermanii vitamin B12 Correspondence K. Iida and M. Kajiwara Department of MedicinalChemistry Meiji Pharmaceutical University 2-522-1 Noshio Kiyose-shi Tokyo 204-8588 Japan Fax 81 424 95 8612 Tel 81 424 95 8611 E-mail iida@ or kajiwara@ Received 18 April2007 revised 14 May 2007 accepted 14 May 2007 The mechanism of the ring contraction process during vitamin B12 biosynthesis by the anaerobe Propionibacterium shermanii was investigated under both aerobic and anaerobic conditions by means of feeding experiments with 8-amino 1-13C levulinic acid a biosynthetic intermediate of tetrapyrrole and 8-amino 1-13C 1 1 4-18O3 levulinic acid in combination with 13C-NMR spectroscopy. We showed that the characteristic mechanism of the ring contraction process the generation of precorrin-3x from formation of the y-lactone from the ring A acetate group at C1 and hydroxylation at C20 by molecular oxygen catalyzed by CobG and the migration of ring D by cleavage of the carbon-oxygen bond at C1 of precorrin-3x in the aerobe Pseudomonas denitrificans was not seen in P. shermanii under aerobic conditions and the mechanism of the ring contraction process in P. sher-manii was the same irrespective of the presence or absence of oxygen. doi The anaerobic organism Propionibacterium shermanii was shown to produce vitamin B12 from D-glucose as a carbon source under bubbling of N2 gas in our previous study 1 . This implies that 8-aminolevulinic acid ALA a biosynthetic intermediate of tetrapyrrole can be produced from D-glucose via the tricarboxylic acid cycle an .

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