[{"from": "human", "value": "Describe this molecule. [C][C][C@@H1][Branch1][#Branch1][O][C@@H1][Ring1][Branch1][C][O][N][C][=N][C][=C][Ring1][Branch1][N][=C][N][C][Ring1][=Branch1][=O]"}, {"from": "gpt", "value": "The molecule has been replaced by a hydrogen. This modification prevents the formation of phosphodiester linkages which are needed for the completion of nucleic acid chains. Didanosine is a potent inhibitor of HIV replication, acting as a chain-terminator of viral DNA by binding to reverse transcriptase; ddI is then metabolized to dideoxyadenosine triphosphate, its putative active metabolite."}]