5,6 dimethylbenzimidazole synthase

5,6-dimethylbenzimidazole synthase (EC 1.14.99.40, BluB) is an enzyme with systematic name FMNH₂ oxidoreductase (5,6-dimethylbenzimidazole forming). This enzyme catalyses the following chemical reaction

FMNH₂ + NADH + H⁺ + O₂ ⇌ 5,6-dimethylbenzimidazole + D-erythrose 4-phosphate + NAD⁺ + other product

The C-2 of 5,6-dimethylbenzimidazole is derived from C-1' of the ribityl group of FMNH₂ and 2-H from the ribityl 1'-pro-S hydrogen.