Reaction performed by the NBOR and the photoreduction of its FMN cofactor. (A) Reaction scheme of the NAD(P)H-dependent reduction of NB to its leuco form. (B) Time-dependent photoreduction of NBOR (time of exposure to light: 1, 0 s; 2, 10 s; 3, 20 s; 4, 100 s; 5, 100 s, followed by the addition of O2) performed as described in Materials and Methods.