    New chain ID            Original chain ID

7nz4-pdb-bundle1.pdb:
           A                        A1
           B                        A2
           C                        B1
           D                        B2

7nz4-pdb-bundle2.pdb:
           A                        C1
           B                        D1
           C                        E1
           D                        E2
           E                        F1
           F                        F2
           G                        G1
           H                        G2
           I                        H1
           J                        H2
