Biosynthesis of vitamin B-12 in anaerobic bacteria. Experiments with Eubacterium limosum and D-erythrose 14C-labeled in different positions.

摘要: The pathway of vitamin B-12 biosynthesis in anaerobic bacteria differs several respects from the found aerobic or aerotolerant microorganisms. aim this investigation was to elucidate formation 5,6-dimethylbenzimidazole part and amide groups bacteria. [15N]Ammonium chloride l-[amido-15N]glutamine a mixture [15N]ammonium sulfate [15N]glycine added fermentations with Eubacterium limosum. isolated these methylated degraded cobinamide 1,5,6-trimethylbenzimidazole. were hydrolyzed nitrogen side chains a, b, c, d, e g trapped as benzamide. 15N incorporation determined by mass spectroscopy. Thus experiment benzamide 1,5,6-trimethylbenzimidazole contained 9.6%15N, whereas 37.5% molecules labeled. 1H-NMR spectrum revealed that ammonium salts glutamine incorporated into N-3 moiety B-12. With both nitrogens became 15N-labeled. These experiments demonstrate E. limosum is not only precursor six corrin ring, but also