[{"from": "human", "value": "Design a molecule that meets the criteria outlined in the description. The molecule is a 2-oxo monocarboxylic acid derived from L-methionine via the action of methionine transaminase. It is functionally related to a butyric acid and a L-methionine. It is a conjugate acid of a 4-methylthio-2-oxobutanoate."}, {"from": "gpt", "value": "[C][S][C][C][C][=Branch1][C][=O][C][=Branch1][C][=O][O]"}]