obsolete phenylalanine 4-hydroxylase (N10-formyl-tetrahydrofolate dependent) activity (obsolete GO:0102433)
OBSOLETE. Catalysis of the reaction: L-phenylalanine + O2 + an N10-formyl-tetrahydrofolate = L-tyrosine + a 10-formyltetrahydrofolate-4a-carbinolamine.