[{"from": "human", "value": "Describe this molecule. [C][=C][C][=Branch1][S][=C][C][=C][Ring1][=Branch1][C][C@H1][Branch1][=Branch1][C][=Branch1][C][=O][O-1][NH3+1][O]"}, {"from": "gpt", "value": "The molecule is a D-alpha-amino acid zwitterion that is D-tyrosine in which a proton has been transferred from the carboxy group to the amino group. It is the major species at pH 7.3. It is a tautomer of a D-tyrosine."}]