[{"from": "human", "value": "Generate a molecule based on the given description. The molecule is a S-alkyl-L-cysteine zwitterion obtained by transfer of a proton from the carboxy to the amino group of S-ethyl-L-cysteine; major species at pH 7.3. It is a tautomer of a S-ethyl-L-cysteine."}, {"from": "gpt", "value": "[C][C][S][C][C@@H1][Branch1][=Branch1][C][=Branch1][C][=O][O-1][NH3+1]"}]