Atomic structure
There is only one chemically distinct structure:
Nc1ncnc2c1ncn2[C@@H]1O[C@H](COP(=O)(O)O[C@H]2[C@@H](O)[C@H](n3cnc4c(N)ncnc43)O[C@@H]2COP(=O)(O)O[C@H]2[C@@H](O)[C@H](n3cnc4c(N)ncnc43)O[C@@H]2CO)[C@@H](O)[C@H]1O