2.5.1.78 1-deoxy-L-glycero-tetrulose 4-phosphate + 5-amino-6-(D-ribitylamino)uracil = 6,7-dimethyl-8-(D-ribityl)lumazine + 2 H2O + phosphate - - 2.5.1.78 1-deoxy-L-glycero-tetrulose 4-phosphate + 5-amino-6-(D-ribitylamino)uracil = 6,7-dimethyl-8-(D-ribityl)lumazine + 2 H2O + phosphate critical involvement of the active-site residues Phe22, His88 and Arg127 in substrate binding and catalysis 738204