Munder M, Vogt J R, Vogler B, Renz P
Institut für Biologische Chemie und Ernährungswissenschaft, Universität Hohenheim, Federal Republic of Germany.
Eur J Biochem. 1992 Mar 1;204(2):679-83. doi: 10.1111/j.1432-1033.1992.tb16681.x.
Experiments on the incorporation of erythrose and formate into the 5,6-dimethylbenzimidazole moiety of vitamin B12 are described. In one experiment, a 1:1 mixture of D-[1-13C]erythrose and D-[1-13C]threose was added to a Eubacterium limosum fermentation. The vitamin B12 formed was methylated at N3 of its 5,6-dimethylbenzimidazole part and degraded to 1,5,6-trimethylbenzimidazole. The 13C-NMR spectrum of this compound exhibited a single prominent signal at 109.5 ppm due to 13C labeling in C7. This shows that C1 of erythrose or threose was originally incorporated exclusively into C4 of the 5,6-dimethylbenzimidazole moiety of vitamin B12. In another experiment, sodium [13C]formate was added to a culture of E. limosum. The vitamin B12 isolated was transformed into 1,5,6-trimethylbenzimidazole as before. The 13C-NMR spectrum also showed one prominent signal at 142.8 ppm, evoked by 13C at C2. These results demonstrate that erythrose is incorporated into the base part of vitamin B12 regiospecifically and that formate is the precursor of the C2.
本文描述了关于将赤藓糖和甲酸掺入维生素B12的5,6-二甲基苯并咪唑部分的实验。在一个实验中，将D-[1-13C]赤藓糖和D-[1-13C]苏糖的1:1混合物添加到黏质真杆菌发酵体系中。形成的维生素B12在其5,6-二甲基苯并咪唑部分的N3位甲基化，并降解为1,5,6-三甲基苯并咪唑。该化合物的13C-NMR谱在109.5 ppm处显示一个单一的突出信号，这是由于C7处的13C标记。这表明赤藓糖或苏糖的C1最初仅掺入维生素B12的5,6-二甲基苯并咪唑部分的C4中。在另一个实验中，将[13C]甲酸钠添加到黏质真杆菌培养物中。分离得到的维生素B12如前所述转化为1,5,6-三甲基苯并咪唑。13C-NMR谱也在142.8 ppm处显示一个突出信号，这是由C2处的13C引起的。这些结果表明，赤藓糖以区域特异性方式掺入维生素B12的碱基部分，并且甲酸是C2的前体。
