An additional structural moiety of FMN, the ribityl group, uses one of its four oxygens for hydrogen bonding, whereas phosphate oxygens form additional hydrogen bonds with Watson–Crick edges of several conserved guanines.
The ribityl component of FMN has a supplementary structural aspect involving one of its oxygen atoms in hydrogen bonding, whereas the phosphate moiety establishes additional interactions with Watson–Crick edges of several invariant guanines.