. "(2-amino-4-hydroxy-7,8-dihydropteridin-6-yl)methyl diphosphate + 4-(beta-D-ribofuranosyl)-aminobenzene-5'-phosphate = diphosphate + 7,8-dihydropterin-6-methyl-4-(beta-D-ribofuranosyl)-aminobenzene-5'-phosphate." .