    New chain ID            Original chain ID

4v73-pdb-bundle1.pdb:
           A                        AB
           B                        AC
           C                        AD
           D                        AE
           E                        AF
           F                        AG
           G                        AH
           H                        AI
           I                        AJ
           J                        AK
           K                        AL
           L                        AM
           M                        AN
           N                        AO
           O                        AP
           P                        AQ
           Q                        AR
           R                        AS
           S                        AT
           T                        AU
           U                        AA
           V                        A1
           W                        A2
           X                        A3
           Y                        BC
           Z                        BD
           a                        BE
           b                        BF
           c                        BG
           d                        BH
           e                        BI
           f                        BJ
           g                        BK
           h                        BL
           i                        BM
           j                        BN
           k                        BO
           l                        BP
           m                        BQ
           n                        BR
           o                        BS
           p                        BT
           q                        BU
           r                        BV
           s                        BW
           t                        BX
           u                        BY
           v                        BZ
           w                        B0
           x                        B1
           y                        B2
           z                        B3
           0                        B4

4v73-pdb-bundle2.pdb:
           A                        BA
           B                        BB
           C                        B5
