[{"from": "human", "value": "What can you tell me about this molecule? [C][Branch1][#Branch2][C][Branch1][=Branch1][C][=Branch1][C][=O][O][N][Se]"}, {"from": "gpt", "value": "The molecule is an unusual amino acid of proteins, the selenium analogue of cysteine, in which a selenium atom replaces sulphur. Involved in the catalytic mechanism of seleno enzymes such as formate dehydrogenase of E. coli and mammalian glutathione peroxidase."}]