    New chain ID            Original chain ID

7rnr-pdb-bundle1.pdb:
           A                         A
           E                         E
           B                         B
           F                         F
           Q                         Q
           Y                         Y
           S                         S
           a                         a
           I                         I
           M                         M
           J                         J

7rnr-pdb-bundle2.pdb:
           N                         N
           R                         R
           Z                         Z
           T                         T
           b                         b
           g                         g
           k                         k
           h                         h
           l                         l
