[{"from": "human", "value": "Could you give me a brief overview of this molecule? [C][=C][Branch1][=Branch1][N][C][=N][Ring1][Branch1][C][C@H1][Branch1][=Branch1][C][=Branch1][C][=O][O-1][NH3+1]"}, {"from": "gpt", "value": "The molecule is a polar amino acid zwitterion restulting from the transfer of a proton from the carboxy group to the alpha-amino group of D-histidine. The major species at pH 7.3. It is a tautomer of a D-histidine."}]