    New chain ID            Original chain ID

7coy-pdb-bundle1.pdb:
           A                        aA
           B                        aB
           C                        aC
           D                        aD
           E                        aE
           F                        aF
           G                        aI
           H                        aJ
           I                        aK
           J                        aL
           K                        aM
           L                        bA
           M                        bB
           N                        bC
           O                        bD
           P                        bE
           Q                        bF
           R                        bI
           S                        bJ
           T                        bK
           U                        bL
           V                        bM
           W                        cA
           X                        cB
           Y                        cC
           Z                        cD
           a                        cE
           b                        cF
           c                        cI
           d                        cJ
           e                        cK
           f                        cL
           g                        cM
