    New chain ID            Original chain ID

7pa7-pdb-bundle1.pdb:
           A                       eee
           B                       AAA
           C                       BBB
           D                       CCC
           E                       DDD
           F                       EEE
           G                       MMM
           H                       NNN
           I                       OOO
           J                       PPP
           K                       QQQ
           L                       aaa
           M                       bbb
           N                       ccc
           O                       ddd
           P                       mmm
           Q                       nnn
           R                       ooo
           S                       ppp
           T                       qqq
