    New chain ID            Original chain ID

9fna-pdb-bundle1.pdb:
           A                         A
           B                        AA
           C                        AB
           D                         B
           E                        BA
           F                        BB
           G                         C
           H                        CA
           I                        CB
           J                         D
           K                        DA
           L                        DB
           M                         E
           N                        EA
           O                        EB
           P                         F
           Q                        FA
           R                        FB
           S                         G
           T                        GA
           U                        GB
           V                         H
           W                        HA
           X                        HB
           Y                         I
           Z                        IA
           a                        IB
           b                         J
           c                        JA
           d                         K
           e                        KA
           f                         L
           g                        LA
           h                         M
           i                        MA
           j                         N
           k                        NA
           l                         O
           m                        OA
           n                         P
           o                        PA
           p                         Q
           q                        QA
           r                         R
           s                        RA
           t                         S
           u                        SA
           v                         T
           w                        TA

9fna-pdb-bundle2.pdb:
           A                        UA
           B                         V
           C                        VA
           D                         W
           E                        WA
           F                         X
           G                        XA
           H                         Y
           I                        YA
           J                         Z
           K                        ZA
