In vitro, catalyzes the highly regiospecific C-3 hydroxylation of L-phenylalanine (L-Phe) to yield 3-hydroxy-L-phenylalanine (meta-Tyr), an amino acid found in bacterial secondary metabolites such as sanglifehrin A and some pacidamycins. Tetrahydrobiopterin (BH4) seems to be the physiological pterin, however the hydroxylase is also able to use 6-methyltetrahydropterin (6-MePH4). (6R)-L-erythro-5,6,7,8-tetrahydrobiopterin + L-phenylalanine + O2 = (4aS,6R)-4a-hydroxy-L-erythro-5,6,7,8-tetrahydrobiopterin + 3-hydroxy-L-phenylalanine kcat is 1.3 min(-1) for L-phenylalanine as substrate. kcat is 1.2 min(-1) for 6-methyltetrahydropterin as substrate. Optimum pH is 6, and the enzyme tends to precipitate gradually below pH 6.5. Belongs to the biopterin-dependent aromatic amino acid hydroxylase family.