Fig. 29.
Creating the dimethylbenzimidazole ligand for B12 from FMN: (a) vitamin B12 with the dimethylbenzimidazole (DMB) as bottom axial ligand to the cobalt atom; (b) BluB acts as a flavin “destructase”, generating DMB and erythrose-4-P from FMN; (c) possible mechanism involving a Fl-4a-OOH and an internal Baeyer-Villiger reaction on the pyrimidine ring of FMN.