    New chain ID            Original chain ID

6zu2-pdb-bundle1.pdb:
           A                       AAA
           B                       BBB
           C                       CCC
           D                       DDD
           E                       EEE
           F                       FFF
           G                       AaA
           H                       BaB
           I                       CaC
           J                       DaD
           K                       EaE
           L                       FaF
