[{"from": "human", "value": "What can you tell me about this molecule? [C][C][Branch1][C][C][C@@H1][Branch1][=Branch1][C][=Branch1][C][=O][O][N][C][C][C][#N]"}, {"from": "gpt", "value": "The molecule is a modified amino acid that arises from acrylonitrile modification of N-terminal amino acid in hemoglobin. It is used as a biomarker of long term or historical exposure to acrylonitrile (a byproduct of smoking cigarettes).  The free amino acid arises from proteolytic degradation of hemoglobin."}]