[{"from": "human", "value": "Please give me some details about this molecule. [C][S][C][C][C][Branch1][=Branch1][C][=Branch1][C][=O][O-1][NH3+1]"}, {"from": "gpt", "value": "The molecule is an amino acid zwitterion arising from transfer of a proton from the carboxy to the amino group of methionine; major species at pH 7.3. It is a tautomer of a methionine."}]