    New chain ID            Original chain ID

8ucr-pdb-bundle1.pdb:
           A                        MT
           B                         A
           C                         X
           D                         Z
           E                         a
           F                         b
           G                         c
           H                         d
           I                         e
           J                         f
           K                         g
           L                         h
           M                         i
           N                         j
           O                         k
           P                         l
           Q                         m
