    New chain ID            Original chain ID

4v7q-pdb-bundle1.pdb:
           A                        AA
           B                        AB
           C                        AC
           D                        AD
           E                        AE
           F                        AF
           G                        AG
           H                        AH
           I                        AI
           J                        AJ
           K                        AK
           L                        AL
           M                        AM
           N                        AN
           O                        AO
           P                        BA
           Q                        BF
           R                        BG
           S                        BH
           T                        BI
           U                        BJ
           V                        BK
           W                        BL
           X                        BM
           Y                        BN
           Z                        BO
           a                        BP
           b                        BQ
           c                        BX
           d                        BY
           e                        BZ
