    New chain ID            Original chain ID

7paa-pdb-bundle1.pdb:
           A                       ZZZ
           B                       AAA
           C                       BBB
           D                       CCC
           E                       DDD
           F                       EEE
           G                       FFF
           H                       GGG
           I                       HHH
           J                       III
           K                       JJJ
           L                       KKK
           M                       aaa
           N                       bbb
           O                       ccc
           P                       ddd
           Q                       eee
           R                       WWW
           S                       XXX
           T                       YYY
