title: Mode of transformation of [1-15N]5-hydroxybenzimidazole and [1-15N]5-hydroxy-6-methylbenzimidazole into the 5,6-dimethylbenzimidazole moiety of vitamin B12.
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).
authors.affiliation: Institut für Biologische Chemie und Ernährungswissenschaft, Universität Hohenheim, Stuttgart, Germany.
authors.forename: B
authors.initials: B
authors.lastname: Schulze
authors.forename: D
authors.initials: D
authors.lastname: Ruoff
authors.forename: B
authors.initials: B
authors.lastname: Volger
authors.forename: P
authors.initials: P
authors.lastname: Renz
mesh_terms: D001562:Benzimidazoles / Q000378:metabolism*; D003038:Cobamides / Q000096:biosynthesis / Q000737:chemistry; D005051:Eubacterium / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D014805:Vitamin B 12 / Q000096:biosynthesis*
chemical_list: D001562:Benzimidazoles; D003038:Cobamides; C084348:5-hydroxy-6-methylbenzimidazole; C036435:5-hydroxybenzimidazole; C015158:5,6-dimethylbenzimidazole; D014805:Vitamin B 12