Vogt J R, Lamm-Kolonko L, Renz P
Institut für Biologische Chemie und Ernährungswissenschaft der Universität Hohenheim, Stuttgart, Federal Republic of Germany.
Eur J Biochem. 1988 Jul 1;174(4):637-40. doi: 10.1111/j.1432-1033.1988.tb14145.x.
In anaerobic microorganisms the origin of C atoms 2 and 4-7 of the 5,6-dimethylbenzimidazole moiety of vitamin B-12 is still unknown. In order to tackle this problem we added several 14C-labeled putative precursors to Eubacterium limosum fermentations. The degradation of the isolated vitamin B-12 revealed that only D-erythrose, 14C-labeled in different positions, was efficiently incorporated into the 5,6-dimethylbenzimidazole part. The 5,6-dimethylbenzimidazole obtained from an experiment with D-[U-14C]erythrose was further degraded. It was found that C-2 was unlabeled, whereas half of the label was located in C-5 plus C-6, and the other half in C-4 plus C-7. These results demonstrate that in E. limosum D-erythrose is a precursor of C-atoms 4, 5, 6 and 7 of the 5,6-dimethylbenzimidazole part of vitamin B-12.
在厌氧微生物中，维生素B-12的5,6-二甲基苯并咪唑部分的C原子2和4至7的来源仍然未知。为了解决这个问题，我们向黏滞真杆菌发酵中添加了几种14C标记的假定前体。分离出的维生素B-12的降解显示，只有在不同位置标记了14C的D-赤藓糖能有效地掺入到5,6-二甲基苯并咪唑部分。用D-[U-14C]赤藓糖进行实验得到的5,6-二甲基苯并咪唑进一步降解。结果发现，C-2未被标记，而一半的标记位于C-5加C-6，另一半位于C-4加C-7。这些结果表明，在黏滞真杆菌中，D-赤藓糖是维生素B-12的5,6-二甲基苯并咪唑部分的C原子4、5、6和7的前体。
