Mode of Transformation of [1-15N]5-hydroxybenzimidazole and [1-15N]5-hydroxy-6-methyl-benzimidazole into the 5,6-dimethylbenzimidazolmoiety of Vitamin B12

Publication Type
Journal contribution
Authors
Schulze, B.; Ruoff, D.; Vogler, B.; Renz, P.
Year of publication
1994
Published in
Biologische Chemie Hoppe-Seyler
Band/Volume
375/
Page (from - to)
785 - 788
Abstract

The transformation of [1-15N]5-hydroxybenzimidazole and [1-15N]5-hydroxy-6-methylbenzimidazole into the 5,6-dimethylbenzimidazole moiety of vitamin B12 by Eubacterium limosum cultures was studied. The vitamin B12 obtained was exclusively 15N-labeled in N-1 of the base part, as revealed by NMR measurements. This indicates that either the unsubstituted 5,6-dimethylbenzimidazole presumably formed is not released from the enzyme until the ribose-5'-phosphate substituent is introduced, or that the precursors are first transformed into their .alpha.-nucleotide-5'-phosphates which then react to form 5,6-dimethylbenzimidazole-.alpha.-D-ribofuranoside-5'-phosphate (.alpha.-ribazole-5'-phosphate).

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