SEARCH Articles Figures Tables Amino acids L-phenylalanine Amino acids Phenylalanine (Phe Amino acids phenylalanine analogues Amino acids phenylalanine metabolism Amino-acid residues phenylalanine Aromatic Amino Acids Phenylalanine, Tyrosine, Histidine, and Tryptophan Phenylalanine essential amino acid Phenylalanine neutral amino acid carrier system