    New chain ID            Original chain ID

4v7n-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                        AP
           Q                        AQ
           R                        AR
           S                        BA
           T                        BB
           U                        BC
           V                        BD
           W                        BE
           X                        BF
           Y                        BG
           Z                        BH
           a                        BI
           b                        BJ
           c                        BK
           d                        BL
           e                        BM

4v7n-pdb-bundle2.pdb:
           A                        BN
           B                        BO
           C                        BP
           D                        BQ
           E                        BR
