SEARCH Articles Figures Tables Aromatic Amino Acids Phenylalanine, Tyrosine, Histidine, and Tryptophan Histidine ligands tyrosine Tyrosine histidine competition Tyrosine, proton transfer to histidine R)- -Umbelactone, isolation from Tyrosine, proton transfer to histidine Ungeremine Tyrosine, proton transfer to histidine enzymes Tyrosine, proton transfer to histidine plants Tyrosine, proton transfer to histidine radicals, in photosystem Tyrosine, proton transfer to histidine synthesis