[Transformation of [5'-3H]riboflavin into 5,6-dimethylbenzimidazole].
The 5,6-dimethylbenzimidazole unit of vitamin B12 is formed from riboflavin via FMN in aerobic and some aerotolerant bacteria. Thereby C-1' of the ribityl side chain gets C-2 of 5,6-dimethylbenzimidazole. Experiments with homogenates of Propionibacterium shermanii on the fate of C-atoms 2' to 5' of the ribityl side chain of riboflavin in this transformation are reported. It was found that [5'-3H]riboflavin leads to radioactive sugar phosphates. These were isolated, dephosphorylated, and separated. Thus 3H-D-fructose and 3H-D-glucose were detected. The degradation of 3H-D-glucose revealed that 14 per cent of the total radioactivity was located in C-1, and 86 per cent in C-6. This indicates that during 5,6-dimethylbenzimidazole biosynthesis a three carbon unit is formed from the ribityl side chain of riboflavin.
Kolonko
B
B
Institut für Biologische Chemie und Ernährungswissenschaft Universität Hohenheim, Stuttgart, Bundesrepublik Deutschland.
Hörig
J A
JA
Renz
P
P
D001562:Benzimidazoles / Q000378:metabolism*; D001711:Biotransformation; D005632:Fructose / Q000378:metabolism; D005947:Glucose / Q000378:metabolism; D007553:Isotope Labeling / Q000379:methods; D011424:Propionibacterium / Q000378:metabolism*; D011865:Radioisotope Dilution Technique; D012256:Riboflavin / Q000138:chemical synthesis / Q000378:metabolism*; D014316:Tritium
D001562:Benzimidazoles; D014316:Tritium; D005632:Fructose; C015158:5,6-dimethylbenzimidazole; D005947:Glucose; D012256:Riboflavin
Umwandlung von [5'-3H]Riboflavin in 5,6-Dimethylbenzimidazol.