[{"from": "human", "value": "What can you tell me about this molecule? [C][O][C][C][N][C][=Branch1][C][=O][C][=C][C][Ring1][=Branch1][=O]"}, {"from": "gpt", "value": "The molecule is a poly(ethylene glycol) derivative that is methoxypoly(ethylene glycol) in which the terminal hydroxy group has been converted to the corresponding 2-maleimidoethyl ether. Used particularly for the mPEGylation of free thiol groups in cysteine residues of proteins. It has a role as a reagent. It is a poly(ethylene glycol) derivative and a member of maleimides."}]