    New chain ID            Original chain ID

8bkz-pdb-bundle1.pdb:
           A                         X
           B                         Y
           C                         A
           D                         B
           E                         C
           F                         D
           G                         E
           H                         F
           I                         G
           J                         H
           K                         I
           L                         J
           M                         K
           N                         L
           O                         M
           P                         N
           Q                         O
           R                         P
           S                         Q
           T                         R
           U                         S
           V                         T
           W                         V
           X                         W
           Y                         Z
           Z                        AA
           a                        BA
           b                        CA
