[{"from": "human", "value": "What can you tell me about this molecule? [C][Branch2][Ring1][Ring1][C][P][Branch1][Branch2][C][C][C][=Branch1][C][=O][O][C][C][C][=Branch1][C][=O][O][C][=Branch1][C][=O][O]"}, {"from": "gpt", "value": "The molecule is an agent used in peptide mapping to reduce cysteine-containing disulfides to thiols."}]